@classmethod
def parse(cls, name, data_size, reader, parsers):
    """given a 4 byte name, data_size int, BitstreamReader
        and dict of {"atom":handler} sub-parsers,
        returns an atom of this class"""
    assert name == b'ftyp'
    return cls(reader.read_bytes(4), reader.read(32), [reader.read_bytes(4) for
        i in range((data_size - 8) // 4)])
