def unify_number_pair_test(self, n):
        """
        Test all permutations of N-combinations of numeric types and ensure
        that the order of types in the sequence is irrelevant.
        """
        ctx = typing.Context()
        for tys in itertools.combinations(types.number_domain, n):
            res = [ctx.unify_types(*comb)
                   for comb in itertools.permutations(tys)]
            first_result = res[0]
            # Sanity check
            self.assertIsInstance(first_result, types.Number)
            # All results must be equal
            for other in res[1:]:
                self.assertEqual(first_result, other)

        Test all permutations of N-combinations of numeric types and ensure
        that the order of types in the sequence is irrelevant.
        
numba/tests/test_typeinfer.py