def map_column(self, keys, func):
        """
        Args:
            keys (list or str): the column name(s) to apply the `func` to
            func (callable): applied to each element in the specified columns
        """
        return [[func(v) for v in self[key]] for key in keys]
def map_column ( self , keys , func ) : return [ [ func ( v ) for v in self [ key ] ] for key in keys ]
Args:
            keys (list or str): the column name(s) to apply the `func` to
            func (callable): applied to each element in the specified columns