docs: 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(index=col.index)
          out[self.col_name] = col.apply(self.get_val, axis=1)
  
          if self.subtype == 'int':
              out[self.col_name] = out[self.col_name].astype(int)
  
          return out