code: def ToDebugString(self):
      
      text_parts = ['Path segment index\tWeight']
      for path_segment_index, weight in self._weight_per_index.items():
        text_parts.append('{0:d}\t\t\t{1:d}'.format(
            path_segment_index, weight))
      text_parts.append('')
  
      text_parts.append('Weight\t\t\tPath segment index(es)')
      for weight, path_segment_indexes in self._indexes_per_weight.items():
        text_parts.append('{0:d}\t\t\t{1!s}'.format(
            weight, path_segment_indexes))
      text_parts.append('')
  
      return '\n'.join(text_parts)
docs: Converts the path segment weights into a debug string.