Returns a column as a Series.

        Parameters
        ----------
        column_name : str

        Returns
        -------
        column : pandas.Series

def get_column(self, column_name):
        """
        Returns a column as a Series.

        Parameters
        ----------
        column_name : str

        Returns
        -------
        column : pandas.Series

        """
        frame = self._call_func()
        return DataFrameWrapper(self.name, frame,
                                copy_col=self.copy_col).get_column(column_name)