code: def _validate_columns(self):
          
          geom_cols = {'the_geom', 'the_geom_webmercator', }
          col_overlap = set(self.style_cols) & geom_cols
          if col_overlap:
              raise ValueError('Style columns cannot be geometry '
                               'columns. `{col}` was chosen.'.format(
                                   col=','.join(col_overlap)))
docs: Validate the options in the styles