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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 sign_nonce(key, nonce):
    ''' sign the server nonce from the WWW-Authenticate header with an authKey'''
    # HMAC.new(key, msg='', digestmod=None)
    return Cryptodome.Hash.HMAC.new(key, nonce, digestmod=Cryptodome.Hash.SHA256).digest()