fix pyStyle2

Author: brkyvz

python/pyspark/sql/dataframe.py

@@ -1341,9 +1341,10 @@ def cov(self, col1, col2):
         if not isinstance(col2, str):
             raise ValueError("col2 should be a string.")
         return self.df._jdf.stat().cov(col1, col2)
-    
+
     cov.__doc__ = DataFrame.cov.__doc__
 
+
 def _test():
     import doctest
     from pyspark.context import SparkContext