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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 _GetPathSegmentIndexForValueWeights(self, value_weights):
 """Retrieves the index of the path segment based on value weights. Args: value_weights: the value weights object (instance of _PathSegmentWeights). Returns: An integer containing the path segment index. Raises: RuntimeError: is no path segment index can be found. """

    largest_weight = value_weights.GetLargestWeight()

    if largest_weight > 0:
      value_weight_indexes = value_weights.GetIndexesForWeight(largest_weight)
    else:
      value_weight_indexes = []

    if value_weight_indexes:
      path_segment_index = value_weight_indexes[0]
    else:
      path_segment_index = value_weights.GetFirstAvailableIndex()

    if path_segment_index is None:
      raise RuntimeError('No path segment index found.')

    return path_segment_index