remove the parens from the cmp() lambda definition (#3526)

* remove the parens from the cmp() lambda definition

https://github.com/PythonCharmers/python-future/pull/298

* remove the parens from the cmp() lambda definition

https://github.com/PythonCharmers/python-future/pull/298

python/compatibility_tests/v2.5.0/tests/google/protobuf/internal/message_test.py

@@ -58,7 +58,7 @@ from google.protobuf import message
 try:
   cmp                                   # Python 2
 except NameError:
-  cmp = lambda(x, y): (x > y) - (x < y)  # Python 3
+  cmp = lambda x, y: (x > y) - (x < y)  # Python 3
 
 # Python pre-2.6 does not have isinf() or isnan() functions, so we have
 # to provide our own.

python/google/protobuf/internal/message_test.py

@@ -59,7 +59,7 @@ except ImportError:
 try:
   cmp                                   # Python 2
 except NameError:
-  cmp = lambda(x, y): (x > y) - (x < y)  # Python 3
+  cmp = lambda x, y: (x > y) - (x < y)  # Python 3
 
 from google.protobuf import map_unittest_pb2
 from google.protobuf import unittest_pb2