Fix error when Interval is rewritten with a tuple

runtime/Python2/src/antlr4/BufferedTokenStream.py

@@ -39,6 +39,8 @@
 # {@link Token#HIDDEN_CHANNEL}, use a filtering token stream such a
 # {@link CommonTokenStream}.</p>
 from io import StringIO
+
+from antlr4.IntervalSet import Interval
 from antlr4.Token import Token
 from antlr4.error.Errors import IllegalStateException
 
@@ -293,18 +295,18 @@ class BufferedTokenStream(TokenStream):
     def getSourceName(self):
         return self.tokenSource.getSourceName()
 
-    # Get the text of all tokens in this buffer.#/
     def getText(self, interval=None):
         """
+        Get the text of all tokens in this buffer.
 
         :param interval:
         :type interval: antlr4.IntervalSet.Interval
-        :return:
+        :return: string
         """
         self.lazyInit()
         self.fill()
         if interval is None:
-            interval = (0, len(self.tokens)-1)
+            interval = Interval(0, len(self.tokens)-1)
         start = interval.start
         if isinstance(start, Token):
             start = start.tokenIndex
@@ -323,9 +325,12 @@ class BufferedTokenStream(TokenStream):
                 buf.write(t.text)
             return buf.getvalue()
 
-
-    # Get all tokens from lexer until EOF#/
     def fill(self):
+        """
+        Get all tokens from lexer until EOF
+
+        :return: None
+        """
         self.lazyInit()
         while self.fetch(1000)==1000:
             pass

runtime/Python2/tests/TestTokenStreamRewriter.py

@@ -528,8 +528,10 @@ class TestTokenStreamRewriter(unittest.TestCase):
 
         self.assertEquals('afoofoo', rewriter.getDefaultText())
 
-    # Test for fix for: https://github.com/antlr/antlr4/issues/550
     def testPreservesOrderOfContiguousInserts(self):
+        """
+        Test for fix for: https://github.com/antlr/antlr4/issues/550
+        """
         input = InputStream('aa')
         lexer = TestLexer(input)
         stream = CommonTokenStream(lexer=lexer)