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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 token(self, value):
 """ Set the Token of the message. :type value: String :param value: the Token :raise AttributeError: if value is longer than 256 """

        if value is None:
            self._token = value
            return
        if not isinstance(value, str):
            value = str(value)
        if len(value) > 256:
            raise AttributeError
        self._token = value