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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 set_public_limits(self):
 """ Set public limits if auth is enabled and user is not authenticated. Also sets default limit for GET, HEAD requests. """

        if self.request.method.upper() in ['GET', 'HEAD']:
            self._query_params.process_int_param('_limit', 20)
        if self._auth_enabled and not getattr(self.request, 'user', None):
            wrappers.set_public_limits(self)