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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 pack_chunk(tag, data):
 """Pack a PNG chunk for serializing to disk"""

        to_check = tag + data
        return (struct.pack(b"!I", len(data)) + to_check +
                struct.pack(b"!I", zlib.crc32(to_check) & 0xFFFFFFFF))