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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 _encryption_context_hash(hasher, encryption_context):
 """Generates the expected hash for the provided encryption context. :param hasher: Existing hasher to use :type hasher: cryptography.hazmat.primitives.hashes.Hash :param dict encryption_context: Encryption context to hash :returns: Complete hash :rtype: bytes """

    serialized_encryption_context = serialize_encryption_context(encryption_context)
    hasher.update(serialized_encryption_context)
    return hasher.finalize()