@classmethod
def get(cls, *args, **kwargs):
    """
        The class method that fetches and instantiates the resource defined by
        the provided pk value. Any other extra keyword arguments are used to
        format the :attr:`Model._path` variable to construct the request URL.

        :param pk: The primary key value for the requested resource.
        :type pk: string

        :rtype: :class:`Model` or None

        """
    auth = kwargs.pop('auth', cls._auth)
    ids = dict(zip(cls._pk, args))
    path = cls._path.format(**ids)
    data = cls._rest_call(url=path, auth=auth).data
    if not data:
        return None
    instance = cls(**data)
    instance._pk_vals = args
    instance._fetched = True
    if auth:
        instance._auth = auth
    return instance
