STYLE: pep8 fix

Author: jreback

pandas/tests/test_window.py

@@ -226,7 +226,7 @@ def test_count_nonnumeric_types(self):
  'dt_nat': [pd.Timestamp('20170101'), pd.Timestamp('20170203'),
  pd.Timestamp(None)],
  'periods_nat': [pd.Period('2012-01'), pd.Period('2012-02'),
- pd.Period(None)]},
+  pd.Period(None)]},
  columns=cols)
 
  expected = DataFrame(