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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 mkNonce(when=None):
 """Generate a nonce with the current timestamp @param when: Unix timestamp representing the issue time of the nonce. Defaults to the current time. @type when: int @returntype: str @returns: A string that should be usable as a one-way nonce @see: time """

    salt = cryptutil.randomString(6, NONCE_CHARS)
    if when is None:
        t = gmtime()
    else:
        t = gmtime(when)

    time_str = strftime(time_fmt, t)
    return time_str + salt