Prepare the transformer to convert data and return the processed table.

        Args:
            col(pandas.DataFrame): Data to transform.

        Returns:
            pandas.DataFrame

def transform(self, col):
        """Prepare the transformer to convert data and return the processed table.

        Args:
            col(pandas.DataFrame): Data to transform.

        Returns:
            pandas.DataFrame
        """

        out = pd.DataFrame()

        # Make sure all nans are handled the same by replacing with None
        column = col[self.col_name].replace({np.nan: None})
        out[self.col_name] = column.apply(self.get_val)

        return out