code: def _get_cells_headers_ids(self, hed, index):
          
          # pylint: disable=no-self-use
  
          ids = []
          for row in hed:
              if row[index].get_tag_name() == 'TH':
                  ids.append(row[index].get_attribute('id'))
          return ids
docs: Returns a list with ids of rows of same column.
  
          :param hed: The list that represents the table header.
          :type hed: list(list(hatemile.util.html.htmldomelement.HTMLDOMElement))
          :param index: The index of columns.
          :type index: int
          :return: The list with ids of rows of same column.
          :rtype: list(str)