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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _GetMostSignificantPathSegmentIndex( self, paths, similarity_weights, occurrence_weights, value_weights):
 """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. """

    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