docs: def get_range_start_line_number(self,rng):
      """
      .. warning:: not implemented
      """
      sys.stderr.write("error unimplemented get_range_start_line\n")
      sys.exit()
      for i in range(0,len(self._lines)):
        if rng.cmp(self._lines[i]['rng'])==0: return i+1
      return None