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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 _mysql_aes_key(key):
 """Format key."""

    final_key = bytearray(16)
    for i, c in enumerate(key):
        final_key[i % 16] ^= key[i] if PY3 else ord(key[i])
    return bytes(final_key)