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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 hash_token(token, salt):
    '''
    Calculates the hash of a token and salt.
    input is unhexlified

    token and salt must contain an even number of hex digits or
    a binascii.Error exception will be raised
    '''
    digest = hashes.Hash(sha(), backend=default_backend())
    digest.update(binascii.unhexlify(token))
    digest.update(binascii.unhexlify(salt))
    return binascii.hexlify(digest.finalize()).decode()