diff --git a/runtime/Python2/src/antlr4/IntervalSet.py b/runtime/Python2/src/antlr4/IntervalSet.py
index e28a556d4..3a55a2631 100644
--- a/runtime/Python2/src/antlr4/IntervalSet.py
+++ b/runtime/Python2/src/antlr4/IntervalSet.py
@@ -97,16 +97,10 @@ class IntervalSet(object):
         if self.intervals is None:
             return False
         else:
-            for i in self.intervals:
-                if item in i:
-                    return True
-            return False
+            return any(item in i for i in self.intervals)
 
     def __len__(self):
-        xlen = 0
-        for i in self.intervals:
-            xlen += len(i)
-        return xlen
+        return sum(len(i) for i in self.intervals)
 
     def removeRange(self, v):
         if v.start==v.stop-1:
@@ -126,7 +120,7 @@ class IntervalSet(object):
                 # check for included range, remove it
                 elif v.start<=i.start and v.stop>=i.stop:
                     self.intervals.pop(k)
-                    k = k - 1 # need another pass
+                    k -= 1 # need another pass
                 # check for lower boundary
                 elif v.start<i.stop:
                     self.intervals[k] = Interval(i.start, v.start)
diff --git a/runtime/Python2/src/antlr4/ListTokenSource.py b/runtime/Python2/src/antlr4/ListTokenSource.py
index 5e5e03a02..52c7bb500 100644
--- a/runtime/Python2/src/antlr4/ListTokenSource.py
+++ b/runtime/Python2/src/antlr4/ListTokenSource.py
@@ -101,9 +101,7 @@ class ListTokenSource(TokenSource):
             line = lastToken.line
             tokenText = lastToken.text
             if tokenText is not None:
-                for c in tokenText:
-                    if c  == '\n':
-                        line += 1
+                line += tokenText.count('\n')
 
             # if no text is available, assume the token did not contain any newline characters.
             return line
diff --git a/runtime/Python2/src/antlr4/PredictionContext.py b/runtime/Python2/src/antlr4/PredictionContext.py
index dae19e9e0..44d382818 100644
--- a/runtime/Python2/src/antlr4/PredictionContext.py
+++ b/runtime/Python2/src/antlr4/PredictionContext.py
@@ -585,15 +585,14 @@ def getCachedPredictionContext(context, contextCache, visited):
         parent = getCachedPredictionContext(context.getParent(i), contextCache, visited)
         if changed or parent is not context.getParent(i):
             if not changed:
-                parents = [None] * len(context)
-                for j in range(0, len(context)):
-                    parents[j] = context.getParent(j)
+                parents = [context.getParent(j) for j in range(len(context))]
                 changed = True
             parents[i] = parent
     if not changed:
         contextCache.add(context)
         visited[context] = context
         return context
+
     updated = None
     if len(parents) == 0:
         updated = PredictionContext.EMPTY
diff --git a/runtime/Python2/src/antlr4/atn/ATNConfigSet.py b/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
index d5a73eb38..a59ada670 100755
--- a/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
+++ b/runtime/Python2/src/antlr4/atn/ATNConfigSet.py
@@ -33,6 +33,7 @@
 # info about the set, with support for combining similar configurations using a
 # graph-structured stack.
 #/
+from functools import reduce
 from io import StringIO
 from antlr4.PredictionContext import merge
 from antlr4.Utils import str_list
@@ -118,9 +119,9 @@ class ATNConfigSet(object):
         h = config.hashCodeForConfigSet()
         l = self.configLookup.get(h, None)
         if l is not None:
-            for c in l:
-                if config.equalsForConfigSet(c):
-                    return c
+            r = next((c for c in l if config.equalsForConfigSet(c)), None)
+            if r is not None:
+                return r
         if l is None:
             l = [config]
             self.configLookup[h] = l
@@ -129,17 +130,10 @@ class ATNConfigSet(object):
         return config
 
     def getStates(self):
-        states = set()
-        for c in self.configs:
-            states.add(c.state)
-        return states
+        return set(cfg.state for cfg in self.configs)
 
     def getPredicates(self):
-        preds = list()
-        for c in self.configs:
-            if c.semanticContext!=SemanticContext.NONE:
-                preds.append(c.semanticContext)
-        return preds
+        return [cfg.semanticContext for cfg in self.configs if cfg.semanticContext!=SemanticContext.NONE]
 
     def get(self, i):
         return self.configs[i]
@@ -181,10 +175,7 @@ class ATNConfigSet(object):
         return self.hashConfigs()
 
     def hashConfigs(self):
-        h = 0
-        for cfg in self.configs:
-            h = hash((h, cfg))
-        return h
+        return reduce(lambda h, cfg: hash((h, cfg)), self.configs, 0)
 
     def __len__(self):
         return len(self.configs)
diff --git a/runtime/Python2/src/antlr4/atn/ATNState.py b/runtime/Python2/src/antlr4/atn/ATNState.py
index 36b8d92f3..d10e22ddb 100644
--- a/runtime/Python2/src/antlr4/atn/ATNState.py
+++ b/runtime/Python2/src/antlr4/atn/ATNState.py
@@ -141,10 +141,7 @@ class ATNState(object):
         return self.stateNumber
 
     def __eq__(self, other):
-        if isinstance(other, ATNState):
-            return self.stateNumber==other.stateNumber
-        else:
-            return False
+        return isinstance(other, ATNState) and self.stateNumber==other.stateNumber
 
     def onlyHasEpsilonTransitions(self):
         return self.epsilonOnlyTransitions
diff --git a/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py b/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
index e847d08f4..2dfa131bb 100644
--- a/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
+++ b/runtime/Python2/src/antlr4/atn/LexerATNSimulator.py
@@ -535,11 +535,7 @@ class LexerATNSimulator(ATNSimulator):
     def addDFAState(self, configs):
 
         proposed = DFAState(configs=configs)
-        firstConfigWithRuleStopState = None
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                firstConfigWithRuleStopState = c
-                break
+        firstConfigWithRuleStopState = next((cfg for cfg in configs if isinstance(cfg.state, RuleStopState)), None)
 
         if firstConfigWithRuleStopState is not None:
             proposed.isAcceptState = True
diff --git a/runtime/Python2/src/antlr4/atn/PredictionMode.py b/runtime/Python2/src/antlr4/atn/PredictionMode.py
index 14280a5b7..0980ba773 100644
--- a/runtime/Python2/src/antlr4/atn/PredictionMode.py
+++ b/runtime/Python2/src/antlr4/atn/PredictionMode.py
@@ -232,10 +232,7 @@ class PredictionMode(object):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def hasConfigInRuleStopState(cls, configs):
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                return True
-        return False
+        return any(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     # Checks if all configurations in {@code configs} are in a
     # {@link RuleStopState}. Configurations meeting this condition have reached
@@ -247,10 +244,7 @@ class PredictionMode(object):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def allConfigsInRuleStopStates(cls, configs):
-        for config in configs:
-            if not isinstance(config.state, RuleStopState):
-                return False
-        return True
+        return all(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     #
     # Full LL prediction termination.
@@ -419,10 +413,7 @@ class PredictionMode(object):
     #
     @classmethod
     def hasNonConflictingAltSet(cls, altsets):
-        for alts in altsets:
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in altsets)
 
     #
     # Determines if any single alternative subset in {@code altsets} contains
@@ -434,10 +425,7 @@ class PredictionMode(object):
     #
     @classmethod
     def hasConflictingAltSet(cls, altsets):
-        for alts in altsets:
-            if len(alts)>1:
-                return True
-        return False
+        return any(len(alts) > 1 for alts in altsets)
 
     #
     # Determines if every alternative subset in {@code altsets} is equivalent.
@@ -448,13 +436,9 @@ class PredictionMode(object):
     #
     @classmethod
     def allSubsetsEqual(cls, altsets):
-        first = None
-        for alts in altsets:
-            if first is None:
-                first = alts
-            elif not alts==first:
-                return False
-        return True
+        if not altsets:
+            return True
+        return all(alts == altsets[0] for alts in altsets[1:])
 
     #
     # Returns the unique alternative predicted by all alternative subsets in
@@ -467,10 +451,8 @@ class PredictionMode(object):
     def getUniqueAlt(cls, altsets):
         all = cls.getAlts(altsets)
         if len(all)==1:
-            for one in all:
-                return one
-        else:
-            return ATN.INVALID_ALT_NUMBER
+            return all.pop()
+        return ATN.INVALID_ALT_NUMBER
 
     # Gets the complete set of represented alternatives for a collection of
     # alternative subsets. This method returns the union of each {@link BitSet}
@@ -481,10 +463,7 @@ class PredictionMode(object):
     #
     @classmethod
     def getAlts(cls, altsets):
-        all = set()
-        for alts in altsets:
-            all = all | alts
-        return all
+        return set.union(*altsets)
 
     #
     # This function gets the conflicting alt subsets from a configuration set.
@@ -528,11 +507,7 @@ class PredictionMode(object):
 
     @classmethod
     def hasStateAssociatedWithOneAlt(cls, configs):
-        x = cls.getStateToAltMap(configs)
-        for alts in x.values():
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in cls.getStateToAltMap(configs).values())
 
     @classmethod
     def getSingleViableAlt(cls, altsets):
diff --git a/runtime/Python2/src/antlr4/atn/SemanticContext.py b/runtime/Python2/src/antlr4/atn/SemanticContext.py
index 021d4770c..b8fe7b1a0 100644
--- a/runtime/Python2/src/antlr4/atn/SemanticContext.py
+++ b/runtime/Python2/src/antlr4/atn/SemanticContext.py
@@ -115,14 +115,7 @@ def orContext(a, b):
         return result
 
 def filterPrecedencePredicates(collection):
-    result = []
-    for context in collection:
-        if isinstance(context, PrecedencePredicate):
-            if result is None:
-                result = []
-            result.append(context)
-    return result
-
+    return [context for context in collection if isinstance(context, PrecedencePredicate)]
 
 class Predicate(SemanticContext):
 
@@ -187,13 +180,11 @@ class AND(SemanticContext):
     def __init__(self, a, b):
         operands = set()
         if isinstance( a, AND):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, AND):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -203,7 +194,7 @@ class AND(SemanticContext):
             reduced = min(precedencePredicates)
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -227,10 +218,7 @@ class AND(SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser, outerContext):
-        for opnd in self.opnds:
-            if not opnd.eval(parser, outerContext):
-                return False
-        return True
+        return all(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser, outerContext):
         differs = False
@@ -277,13 +265,11 @@ class OR (SemanticContext):
     def __init__(self, a, b):
         operands = set()
         if isinstance( a, OR):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, OR):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -291,10 +277,10 @@ class OR (SemanticContext):
         if len(precedencePredicates)>0:
             # interested in the transition with the highest precedence
             s = sorted(precedencePredicates)
-            reduced = s[len(s)-1]
+            reduced = s[-1]
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -315,10 +301,7 @@ class OR (SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser, outerContext):
-        for opnd in self.opnds:
-            if opnd.eval(parser, outerContext):
-                return True
-        return False
+        return any(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser, outerContext):
         differs = False
diff --git a/runtime/Python2/src/antlr4/dfa/DFAState.py b/runtime/Python2/src/antlr4/dfa/DFAState.py
index 85ccac106..7045f7c22 100644
--- a/runtime/Python2/src/antlr4/dfa/DFAState.py
+++ b/runtime/Python2/src/antlr4/dfa/DFAState.py
@@ -105,14 +105,9 @@ class DFAState(object):
     # Get the set of all alts mentioned by all ATN configurations in this
     #  DFA state.
     def getAltSet(self):
-        alts = set()
         if self.configs is not None:
-            for c in self.configs:
-                alts.add(c.alt)
-        if len(alts)==0:
-            return None
-        else:
-            return alts
+            return set(cfg.alt for cfg in self.configs) or None
+        return None
 
     def __hash__(self):
         return hash(self.configs)
diff --git a/runtime/Python2/src/antlr4/tree/Trees.py b/runtime/Python2/src/antlr4/tree/Trees.py
index d48f4a904..00a322b45 100644
--- a/runtime/Python2/src/antlr4/tree/Trees.py
+++ b/runtime/Python2/src/antlr4/tree/Trees.py
@@ -129,8 +129,7 @@ class Trees(object):
 
     @classmethod
     def descendants(cls, t):
-        nodes = []
-        nodes.append(t)
+        nodes = [t]
         for i in range(0, t.getChildCount()):
             nodes.extend(cls.descendants(t.getChild(i)))
         return nodes
diff --git a/runtime/Python2/src/antlr4/xpath/XPath.py b/runtime/Python2/src/antlr4/xpath/XPath.py
index eee87da6f..e138d3cdf 100644
--- a/runtime/Python2/src/antlr4/xpath/XPath.py
+++ b/runtime/Python2/src/antlr4/xpath/XPath.py
@@ -289,12 +289,7 @@ class XPathRuleElement(XPathElement):
 
     def evaluate(self, t):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, ParserRuleContext ):
-                if (c.ruleIndex == self.ruleIndex ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, ParserRuleContext) and (c.ruleIndex == self.ruleIndex) == (not self.invert)]
 
 class XPathTokenAnywhereElement(XPathElement):
 
@@ -314,12 +309,8 @@ class XPathTokenElement(XPathElement):
 
     def evaluate(self, t):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, TerminalNode):
-                if (c.symbol.type == self.tokenType ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, TerminalNode) and (c.symbol.type == self.tokenType) == (not self.invert)]
+
 
 class XPathWildcardAnywhereElement(XPathElement):
 
@@ -343,4 +334,4 @@ class XPathWildcardElement(XPathElement):
         if self.invert:
             return list() # !* is weird but valid (empty)
         else:
-            return Trees.getChildren(t)
\ No newline at end of file
+            return Trees.getChildren(t)
diff --git a/runtime/Python3/src/antlr4/IntervalSet.py b/runtime/Python3/src/antlr4/IntervalSet.py
index e5f535f45..980509821 100644
--- a/runtime/Python3/src/antlr4/IntervalSet.py
+++ b/runtime/Python3/src/antlr4/IntervalSet.py
@@ -84,16 +84,10 @@ class IntervalSet(object):
         if self.intervals is None:
             return False
         else:
-            for i in self.intervals:
-                if item in i:
-                    return True
-            return False
+            return any(item in i for i in self.intervals)
 
     def __len__(self):
-        xlen = 0
-        for i in self.intervals:
-            xlen += len(i)
-        return xlen
+        return sum(len(i) for i in self.intervals)
 
     def removeRange(self, v):
         if v.start==v.stop-1:
@@ -113,7 +107,7 @@ class IntervalSet(object):
                 # check for included range, remove it
                 elif v.start<=i.start and v.stop>=i.stop:
                     self.intervals.pop(k)
-                    k = k - 1 # need another pass
+                    k -= 1  # need another pass
                 # check for lower boundary
                 elif v.start<i.stop:
                     self.intervals[k] = range(i.start, v.start)
diff --git a/runtime/Python3/src/antlr4/ListTokenSource.py b/runtime/Python3/src/antlr4/ListTokenSource.py
index c0b929a8d..748085b99 100644
--- a/runtime/Python3/src/antlr4/ListTokenSource.py
+++ b/runtime/Python3/src/antlr4/ListTokenSource.py
@@ -101,9 +101,7 @@ class ListTokenSource(TokenSource):
             line = lastToken.line
             tokenText = lastToken.text
             if tokenText is not None:
-                for c in tokenText:
-                    if c  == '\n':
-                        line += 1
+                line += tokenText.count('\n')
 
             # if no text is available, assume the token did not contain any newline characters.
             return line
diff --git a/runtime/Python3/src/antlr4/PredictionContext.py b/runtime/Python3/src/antlr4/PredictionContext.py
index 6cfc08052..0cfc8896c 100644
--- a/runtime/Python3/src/antlr4/PredictionContext.py
+++ b/runtime/Python3/src/antlr4/PredictionContext.py
@@ -581,15 +581,14 @@ def getCachedPredictionContext(context:PredictionContext, contextCache:Predictio
         parent = getCachedPredictionContext(context.getParent(i), contextCache, visited)
         if changed or parent is not context.getParent(i):
             if not changed:
-                parents = [None] * len(context)
-                for j in range(0, len(context)):
-                    parents[j] = context.getParent(j)
+                parents = [context.getParent(j) for j in range(len(context))]
                 changed = True
             parents[i] = parent
     if not changed:
         contextCache.add(context)
         visited[context] = context
         return context
+
     updated = None
     if len(parents) == 0:
         updated = PredictionContext.EMPTY
diff --git a/runtime/Python3/src/antlr4/atn/ATNConfigSet.py b/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
index e499ac947..8145bb466 100755
--- a/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
+++ b/runtime/Python3/src/antlr4/atn/ATNConfigSet.py
@@ -34,6 +34,7 @@
 # graph-structured stack.
 #/
 from io import StringIO
+from functools import reduce
 from antlr4.PredictionContext import PredictionContext, merge
 from antlr4.Utils import str_list
 from antlr4.atn.ATN import ATN
@@ -121,9 +122,9 @@ class ATNConfigSet(object):
         h = config.hashCodeForConfigSet()
         l = self.configLookup.get(h, None)
         if l is not None:
-            for c in l:
-                if config.equalsForConfigSet(c):
-                    return c
+            r = next((cfg for cfg in l if config.equalsForConfigSet(cfg)), None)
+            if r is not None:
+                return r
         if l is None:
             l = [config]
             self.configLookup[h] = l
@@ -132,17 +133,10 @@ class ATNConfigSet(object):
         return config
 
     def getStates(self):
-        states = set()
-        for c in self.configs:
-            states.add(c.state)
-        return states
+        return set(c.state for c in self.configs)
 
     def getPredicates(self):
-        preds = list()
-        for c in self.configs:
-            if c.semanticContext!=SemanticContext.NONE:
-                preds.append(c.semanticContext)
-        return preds
+        return list(cfg.semanticContext for cfg in self.configs if cfg.semanticContext!=SemanticContext.NONE)
 
     def get(self, i:int):
         return self.configs[i]
@@ -184,10 +178,7 @@ class ATNConfigSet(object):
         return self.hashConfigs()
 
     def hashConfigs(self):
-        h = 0
-        for cfg in self.configs:
-            h = hash((h, cfg))
-        return h
+        return reduce(lambda h, cfg: hash((h, cfg)), self.configs, 0)
 
     def __len__(self):
         return len(self.configs)
diff --git a/runtime/Python3/src/antlr4/atn/ATNState.py b/runtime/Python3/src/antlr4/atn/ATNState.py
index 446512193..6dd89f020 100644
--- a/runtime/Python3/src/antlr4/atn/ATNState.py
+++ b/runtime/Python3/src/antlr4/atn/ATNState.py
@@ -143,10 +143,7 @@ class ATNState(object):
         return self.stateNumber
 
     def __eq__(self, other):
-        if isinstance(other, ATNState):
-            return self.stateNumber==other.stateNumber
-        else:
-            return False
+        return isinstance(other, ATNState) and self.stateNumber==other.stateNumber
 
     def onlyHasEpsilonTransitions(self):
         return self.epsilonOnlyTransitions
diff --git a/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py b/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
index 9e7cff144..f5a649a94 100644
--- a/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
+++ b/runtime/Python3/src/antlr4/atn/LexerATNSimulator.py
@@ -542,11 +542,7 @@ class LexerATNSimulator(ATNSimulator):
     def addDFAState(self, configs:ATNConfigSet) -> DFAState:
 
         proposed = DFAState(configs=configs)
-        firstConfigWithRuleStopState = None
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                firstConfigWithRuleStopState = c
-                break
+        firstConfigWithRuleStopState = next((cfg for cfg in configs if isinstance(cfg.state, RuleStopState)), None)
 
         if firstConfigWithRuleStopState is not None:
             proposed.isAcceptState = True
diff --git a/runtime/Python3/src/antlr4/atn/PredictionMode.py b/runtime/Python3/src/antlr4/atn/PredictionMode.py
index 03ca896c7..67039c728 100644
--- a/runtime/Python3/src/antlr4/atn/PredictionMode.py
+++ b/runtime/Python3/src/antlr4/atn/PredictionMode.py
@@ -235,10 +235,7 @@ class PredictionMode(Enum):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def hasConfigInRuleStopState(cls, configs:ATNConfigSet):
-        for c in configs:
-            if isinstance(c.state, RuleStopState):
-                return True
-        return False
+        return any(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     # Checks if all configurations in {@code configs} are in a
     # {@link RuleStopState}. Configurations meeting this condition have reached
@@ -250,10 +247,7 @@ class PredictionMode(Enum):
     # {@link RuleStopState}, otherwise {@code false}
     @classmethod
     def allConfigsInRuleStopStates(cls, configs:ATNConfigSet):
-        for config in configs:
-            if not isinstance(config.state, RuleStopState):
-                return False
-        return True
+        return all(isinstance(cfg.state, RuleStopState) for cfg in configs)
 
     #
     # Full LL prediction termination.
@@ -422,10 +416,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def hasNonConflictingAltSet(cls, altsets:list):
-        for alts in altsets:
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in altsets)
 
     #
     # Determines if any single alternative subset in {@code altsets} contains
@@ -437,10 +428,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def hasConflictingAltSet(cls, altsets:list):
-        for alts in altsets:
-            if len(alts)>1:
-                return True
-        return False
+        return any(len(alts) > 1 for alts in altsets)
 
     #
     # Determines if every alternative subset in {@code altsets} is equivalent.
@@ -451,13 +439,10 @@ class PredictionMode(Enum):
     #
     @classmethod
     def allSubsetsEqual(cls, altsets:list):
-        first = None
-        for alts in altsets:
-            if first is None:
-                first = alts
-            elif not alts==first:
-                return False
-        return True
+        if not altsets:
+            return True
+        first = next(iter(altsets))
+        return all(alts == first for alts in iter(altsets))
 
     #
     # Returns the unique alternative predicted by all alternative subsets in
@@ -470,10 +455,8 @@ class PredictionMode(Enum):
     def getUniqueAlt(cls, altsets:list):
         all = cls.getAlts(altsets)
         if len(all)==1:
-            for one in all:
-                return one
-        else:
-            return ATN.INVALID_ALT_NUMBER
+            return next(iter(all))
+        return ATN.INVALID_ALT_NUMBER
 
     # Gets the complete set of represented alternatives for a collection of
     # alternative subsets. This method returns the union of each {@link BitSet}
@@ -484,10 +467,7 @@ class PredictionMode(Enum):
     #
     @classmethod
     def getAlts(cls, altsets:list):
-        all = set()
-        for alts in altsets:
-            all = all | alts
-        return all
+        return set.union(*altsets)
 
     #
     # This function gets the conflicting alt subsets from a configuration set.
@@ -531,11 +511,7 @@ class PredictionMode(Enum):
 
     @classmethod
     def hasStateAssociatedWithOneAlt(cls, configs:ATNConfigSet):
-        x = cls.getStateToAltMap(configs)
-        for alts in x.values():
-            if len(alts)==1:
-                return True
-        return False
+        return any(len(alts) == 1 for alts in cls.getStateToAltMap(configs).values())
 
     @classmethod
     def getSingleViableAlt(cls, altsets:list):
diff --git a/runtime/Python3/src/antlr4/atn/SemanticContext.py b/runtime/Python3/src/antlr4/atn/SemanticContext.py
index c012e35c2..d69165e4d 100644
--- a/runtime/Python3/src/antlr4/atn/SemanticContext.py
+++ b/runtime/Python3/src/antlr4/atn/SemanticContext.py
@@ -116,13 +116,7 @@ def orContext(a:SemanticContext, b:SemanticContext):
         return result
 
 def filterPrecedencePredicates(collection:list):
-    result = []
-    for context in collection:
-        if isinstance(context, PrecedencePredicate):
-            if result is None:
-                result = []
-            result.append(context)
-    return result
+    return [context for context in collection if isinstance(context, PrecedencePredicate)]
 
 
 class Predicate(SemanticContext):
@@ -188,13 +182,11 @@ class AND(SemanticContext):
     def __init__(self, a:SemanticContext, b:SemanticContext):
         operands = set()
         if isinstance( a, AND ):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, AND ):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -204,7 +196,7 @@ class AND(SemanticContext):
             reduced = min(precedencePredicates)
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -227,11 +219,8 @@ class AND(SemanticContext):
     # The evaluation of predicates by this context is short-circuiting, but
     # unordered.</p>
     #
-    def eval(self, parser:Recognizer , outerContext:RuleContext ):
-        for opnd in self.opnds:
-            if not opnd.eval(parser, outerContext):
-                return False
-        return True
+    def eval(self, parser:Recognizer, outerContext:RuleContext):
+        return all(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser:Recognizer, outerContext:RuleContext):
         differs = False
@@ -278,13 +267,11 @@ class OR (SemanticContext):
     def __init__(self, a:SemanticContext, b:SemanticContext):
         operands = set()
         if isinstance( a, OR ):
-            for o in a.opnds:
-                operands.add(o)
+            operands.update(a.opnds)
         else:
             operands.add(a)
         if isinstance( b, OR ):
-            for o in b.opnds:
-                operands.add(o)
+            operands.update(b.opnds)
         else:
             operands.add(b)
 
@@ -292,10 +279,10 @@ class OR (SemanticContext):
         if len(precedencePredicates)>0:
             # interested in the transition with the highest precedence
             s = sorted(precedencePredicates)
-            reduced = s[len(s)-1]
+            reduced = s[-1]
             operands.add(reduced)
 
-        self.opnds = [ o for o in operands ]
+        self.opnds = list(operands)
 
     def __eq__(self, other):
         if self is other:
@@ -316,10 +303,7 @@ class OR (SemanticContext):
     # unordered.</p>
     #
     def eval(self, parser:Recognizer, outerContext:RuleContext):
-        for opnd in self.opnds:
-            if opnd.eval(parser, outerContext):
-                return True
-        return False
+        return any(opnd.eval(parser, outerContext) for opnd in self.opnds)
 
     def evalPrecedence(self, parser:Recognizer, outerContext:RuleContext):
         differs = False
diff --git a/runtime/Python3/src/antlr4/dfa/DFAState.py b/runtime/Python3/src/antlr4/dfa/DFAState.py
index 1ab5a0e77..9ad996384 100644
--- a/runtime/Python3/src/antlr4/dfa/DFAState.py
+++ b/runtime/Python3/src/antlr4/dfa/DFAState.py
@@ -104,14 +104,9 @@ class DFAState(object):
     # Get the set of all alts mentioned by all ATN configurations in this
     #  DFA state.
     def getAltSet(self):
-        alts = set()
         if self.configs is not None:
-            for c in self.configs:
-                alts.add(c.alt)
-        if len(alts)==0:
-            return None
-        else:
-            return alts
+            return set(cfg.alt for cfg in self.configs) or None
+        return None
 
     def __hash__(self):
         return hash(self.configs)
diff --git a/runtime/Python3/src/antlr4/tree/Trees.py b/runtime/Python3/src/antlr4/tree/Trees.py
index 101df6d9a..42fde282b 100644
--- a/runtime/Python3/src/antlr4/tree/Trees.py
+++ b/runtime/Python3/src/antlr4/tree/Trees.py
@@ -130,8 +130,7 @@ class Trees(object):
 
     @classmethod
     def descendants(cls, t:ParseTree):
-        nodes = []
-        nodes.append(t)
+        nodes = [t]
         for i in range(0, t.getChildCount()):
             nodes.extend(cls.descendants(t.getChild(i)))
         return nodes
diff --git a/runtime/Python3/src/antlr4/xpath/XPath.py b/runtime/Python3/src/antlr4/xpath/XPath.py
index 6b41a943a..6d3d825a5 100644
--- a/runtime/Python3/src/antlr4/xpath/XPath.py
+++ b/runtime/Python3/src/antlr4/xpath/XPath.py
@@ -290,12 +290,8 @@ class XPathRuleElement(XPathElement):
 
     def evaluate(self, t:ParseTree):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, ParserRuleContext ):
-                if (c.ruleIndex == self.ruleIndex ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, ParserRuleContext) and (c.ruleIndex == self.ruleIndex) == (not self.invert)]
+
 
 class XPathTokenAnywhereElement(XPathElement):
 
@@ -315,12 +311,8 @@ class XPathTokenElement(XPathElement):
 
     def evaluate(self, t:ParseTree):
         # return all children of t that match nodeName
-        nodes = []
-        for c in Trees.getChildren(t):
-            if isinstance(c, TerminalNode):
-                if (c.symbol.type == self.tokenType ) == (not self.invert):
-                    nodes.append(c)
-        return nodes
+        return [c for c in Trees.getChildren(t) if isinstance(c, TerminalNode) and (c.symbol.type == self.tokenType) == (not self.invert)]
+
 
 class XPathWildcardAnywhereElement(XPathElement):
 
diff --git a/tool/resources/org/antlr/v4/tool/templates/codegen/Python2/Python2.stg b/tool/resources/org/antlr/v4/tool/templates/codegen/Python2/Python2.stg
index a9ba41f8d..f92dd4870 100644
--- a/tool/resources/org/antlr/v4/tool/templates/codegen/Python2/Python2.stg
+++ b/tool/resources/org/antlr/v4/tool/templates/codegen/Python2/Python2.stg
@@ -319,7 +319,7 @@ self.state = <choice.stateNumber>
 token = self._input.LA(1)
 <choice.altLook,alts:{look,alt| <cases(ttypes=look)>
     <alt>
-	}; separator="\nel">
+    pass}; separator="\nel">
 else:
     <error>
 
diff --git a/tool/resources/org/antlr/v4/tool/templates/codegen/Python3/Python3.stg b/tool/resources/org/antlr/v4/tool/templates/codegen/Python3/Python3.stg
index 5f3dd5505..3a7a1d1f6 100644
--- a/tool/resources/org/antlr/v4/tool/templates/codegen/Python3/Python3.stg
+++ b/tool/resources/org/antlr/v4/tool/templates/codegen/Python3/Python3.stg
@@ -327,7 +327,7 @@ self.state = <choice.stateNumber>
 token = self._input.LA(1)
 <choice.altLook,alts:{look,alt| <cases(ttypes=look)>
     <alt>
-	}; separator="\nel">
+    pass}; separator="\nel">
 else:
     <error>