code: def _GetMostSignificantPathSegmentIndex(
        self, paths, similarity_weights, occurrence_weights, value_weights):
      
      if not paths:
        raise ValueError('Missing paths.')
  
      number_of_paths = len(paths)
  
      path_segment_index = None
      if number_of_paths == 1:
        path_segment_index = self._GetPathSegmentIndexForValueWeights(
            value_weights)
  
      elif number_of_paths == 2:
        path_segment_index = self._GetPathSegmentIndexForOccurrenceWeights(
            occurrence_weights, value_weights)
  
      elif number_of_paths > 2:
        path_segment_index = self._GetPathSegmentIndexForSimilarityWeights(
            similarity_weights, occurrence_weights, value_weights)
  
      return path_segment_index
docs: Retrieves the index of the most significant path segment.
  
      Args:
        paths: a list of strings containing the paths.
        similarity_weights: the similarity weights object (instance of
                            _PathSegmentWeights).
        occurrence_weights: the occurrence weights object (instance of
                            _PathSegmentWeights).
        value_weights: the value weights object (instance of _PathSegmentWeights).
  
      Returns:
        An integer containing the path segment index.
  
      Raises:
        ValueError: when paths is an empty list.