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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 update(self, sha, force=False):
 """Update this reference. :param str sha: (required), sha of the reference :param bool force: (optional), force the update or not :returns: bool """

        data = {'sha': sha, 'force': force}
        json = self._json(self._patch(self._api, data=dumps(data)), 200)
        if json:
            self._update_(json)
            return True
        return False