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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 decrypt(data, key):
    '''decrypt the data with the key'''
    data_len = len(data)
    data = ffi.from_buffer(data)
    key = ffi.from_buffer(__tobytes(key))
    out_len = ffi.new('size_t *')
    result = lib.xxtea_decrypt(data, data_len, key, out_len)
    ret = ffi.buffer(result, out_len[0])[:]
    lib.free(result)
    return ret