docs: def reverse_transform(self, col):
          """Converts data back into original format.
  
          Args:
              col(pandas.DataFrame): Data to transform.
  
          Returns:
              pandas.DataFrame
          """
          output = pd.DataFrame()
          new_name = '?' + self.col_name
  
          col.loc[col[new_name] == 0, self.col_name] = np.nan
          output[self.col_name] = col[self.col_name]
          return output