def METHOD_NAME(block_difficulty=bytes([0] * 32),
           cumulative_difficulty=bytes([0] * 32),
           child_headerhashes=None):
    block_meta_data = BlockMetadata()
    block_meta_data._data.block_difficulty = block_difficulty
    block_meta_data._data.cumulative_difficulty = cumulative_difficulty
    if child_headerhashes:
        for headerhash in child_headerhashes:
            block_meta_data._data.child_headerhashes.append(headerhash)
    return block_meta_data