code: def append(self, val):
          
          # pylint: disable=arguments-differ
          _lists = self._lists
          _maxes = self._maxes
  
          if not _maxes:
              _maxes.append(val)
              _lists.append([val])
              self._len = 1
              return
  
          pos = len(_lists) - 1
  
          if val < _lists[pos][-1]:
              msg = '{0!r} not in sort order at index {1}'.format(val, self._len)
              raise ValueError(msg)
  
          _maxes[pos] = val
          _lists[pos].append(val)
          self._len += 1
          self._expand(pos)
docs: Append the element *val* to the list. Raises a ValueError if the *val*
          would violate the sort order.