code: def parse_has_combinator(self, sel, m, has_selector, selectors, rel_type, index):
          
  
          combinator = m.group('relation').strip()
          if not combinator:
              combinator = WS_COMBINATOR
          if combinator == COMMA_COMBINATOR:
              if not has_selector:
                  # If we've not captured any selector parts, the comma is either at the beginning of the pattern
                  # or following another comma, both of which are unexpected. Commas must split selectors.
                  raise SelectorSyntaxError(
                      "The combinator '{}' at postion {}, must have a selector before it".format(combinator, index),
                      self.pattern,
                      index
                  )
              sel.rel_type = rel_type
              selectors[-1].relations.append(sel)
              rel_type = ":" + WS_COMBINATOR
              selectors.append(_Selector())
          else:
              if has_selector:
                  # End the current selector and associate the leading combinator with this selector.
                  sel.rel_type = rel_type
                  selectors[-1].relations.append(sel)
              elif rel_type[1:] != WS_COMBINATOR:
                  # It's impossible to have two whitespace combinators after each other as the patterns
                  # will gobble up trailing whitespace. It is also impossible to have a whitespace
                  # combinator after any other kind for the same reason. But we could have
                  # multiple non-whitespace combinators. So if the current combinator is not a whitespace,
                  # then we've hit the multiple combinator case, so we should fail.
                  raise SelectorSyntaxError(
                      'The multiple combinators at position {}'.format(index),
                      self.pattern,
                      index
                  )
              # Set the leading combinator for the next selector.
              rel_type = ':' + combinator
          sel = _Selector()
  
          has_selector = False
          return has_selector, sel, rel_type
docs: Parse combinator tokens.