run black on test_source_multiline_block.py

testing/code/test_source_multiline_block.py

@@ -12,10 +12,13 @@ def test_getstartingblock_multiline():
     see hhatto/autopep8#307). It was considered better to just move this single test to its own
     file and exclude it from autopep8 than try to complicate things.
     """
+
     class A(object):
+
         def __init__(self, *args):
             frame = sys._getframe(1)
             self.source = _pytest._code.Frame(frame).statement
+
     # fmt: off
     x = A('x',
           'y'