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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 program_rtr_default_gw(self, tenant_id, rout_id, gw):
 """Program the default gateway of a router. """

        args = ['route', 'add', 'default', 'gw', gw]
        ret = self.program_rtr(args, rout_id)
        if not ret:
            LOG.error("Program router returned error for %s", rout_id)
            return False
        return True