def unbounded(self):
        """Whether solution is unbounded"""
        self._check_valid()

        status = self._problem._p.Status
        if (status == gurobipy.GRB.INF_OR_UNBD and
                self._problem._p.params.DualReductions):
            # Disable dual reductions to obtain a definitve answer
            self._problem._p.params.DualReductions = 0
            try:
                self._problem._p.optimize()
            finally:
                self._problem._p.params.DualReductions = 1

            status = self._problem._p.Status
        return status == gurobipy.GRB.UNBOUNDED
Whether solution is unbounded