code: def _sequence_range_check(self, result, last):
          
  
          removed = False
          first = result[-2]
          v1 = ord(first[1:2] if len(first) > 1 else first)
          v2 = ord(last[1:2] if len(last) > 1 else last)
          if v2 < v1:
              result.pop()
              result.pop()
              removed = True
          else:
              result.append(last)
          return removed
docs: If range backwards, remove it.
  
          A bad range will cause the regular expression to fail,
          so we need to remove it, but return that we removed it
          so the caller can know the sequence wasn't empty.
          Caller will have to craft a sequence that makes sense
          if empty at the end with either an impossible sequence
          for inclusive sequences or a sequence that matches
          everything for an exclusive sequence.