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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 singleton(cls, session, include=None):
 """Get the a singleton API resource. Some Helium API resources are singletons. The authorized user and organization for a given API key are examples of this. .. code-block:: python authorized_user = User.singleton(session) will retrieve the authorized user for the given :class:`Session` Keyword Args: include: Resource classes to include """

        params = build_request_include(include, None)
        url = session._build_url(cls._resource_path())
        process = cls._mk_one(session, singleton=True, include=include)
        return session.get(url, CB.json(200, process), params=params)