docs: def calculate_intervals(chunk_sizes):
          """Calculate intervals for a given chunk sizes.
  
          :param list chunk_sizes: List of chunk sizes.
          :return: Tuple of intervals.
          :rtype: :py:class:`tuple`
          """
          start_indexes = [sum(chunk_sizes[:i]) for i in range(0, len(chunk_sizes))]
          end_indexes = [sum(chunk_sizes[:i+1]) for i in range(0, len(chunk_sizes))]
          return tuple(zip(start_indexes, end_indexes))