Endpoint: /tag/<id>/update.json

        Updates a tag with the specified parameters.
        Returns the updated tag object.

def update(self, tag, **kwds):
        """
        Endpoint: /tag/<id>/update.json

        Updates a tag with the specified parameters.
        Returns the updated tag object.
        """
        result = self._client.post("/tag/%s/update.json" %
                                   self._quote_url(self._extract_id(tag)),
                                   **kwds)["result"]
        return Tag(self._client, result)