fix minor styling issue in tests

tests/test_signals.py

@@ -39,7 +39,6 @@ class SignalTests(unittest.TestCase):
             def post_init(cls, sender, document, **kwargs):
                 signal_output.append('post_init signal, %s, document._created = %s' % (document, document._created))
 
-
             @classmethod
             def pre_save(cls, sender, document, **kwargs):
                 signal_output.append('pre_save signal, %s' % document)
@@ -247,7 +246,7 @@ class SignalTests(unittest.TestCase):
         def load_existing_author():
             a  = self.Author(name='Bill Shakespeare')
             a.save()
-            self.get_signal_output(lambda: None) # eliminate signal output
+            self.get_signal_output(lambda: None)  # eliminate signal output
             a1 = self.Author.objects(name='Bill Shakespeare')[0]
 
         self.assertEqual(self.get_signal_output(create_author), [
@@ -431,5 +430,6 @@ class SignalTests(unittest.TestCase):
             {}
         ])
 
+
 if __name__ == '__main__':
     unittest.main()