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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 header_length(header):
 """Calculates the ciphertext message header length, given a complete header. :param header: Complete message header object :type header: aws_encryption_sdk.structures.MessageHeader :rtype: int """

    # Because encrypted data key lengths may not be knowable until the ciphertext
    #  is received from the providers, just serialize the header directly.
    header_length = len(serialize_header(header))
    header_length += header.algorithm.iv_len  # Header Authentication IV
    header_length += header.algorithm.auth_len  # Header Authentication Tag
    return header_length