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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 for_user(cls, user):
 """ Returns an authorization token for the given user that will be provided after authenticating the user's credentials. """

        user_id = getattr(user, api_settings.USER_ID_FIELD)
        if not isinstance(user_id, int):
            user_id = str(user_id)

        token = cls()
        token[api_settings.USER_ID_CLAIM] = user_id

        return token