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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 deserialize_non_framed_values(stream, header, verifier=None):
 """Deserializes the IV and body length from a non-framed stream. :param stream: Source data stream :type stream: io.BytesIO :param header: Deserialized header :type header: aws_encryption_sdk.structures.MessageHeader :param verifier: Signature verifier object (optional) :type verifier: aws_encryption_sdk.internal.crypto.Verifier :returns: IV and Data Length values for body :rtype: tuple of bytes and int """

    _LOGGER.debug("Starting non-framed body iv/tag deserialization")
    (data_iv, data_length) = unpack_values(">{}sQ".format(header.algorithm.iv_len), stream, verifier)
    return data_iv, data_length