{in: "_"},
	{in: "0_"},
	{in: "_0"},
	{in: "-1__0"},
	{in: "0x10_"},
	{in: "1_000", base: 10}, // separators are not permitted for bases != 0
	{in: "d_e_a_d", base: 16},

	// valid inputs
	{"0", "0", 0, 0, true},
	{"0", "0", 10, 0, true},
	{"0", "0", 16, 0, true},
	{"+0", "0", 0, 0, true},
	{"-0", "0", 0, 0, true},
	{"10", "10", 0, 10, true},

	// (smoke tests only - a comprehensive set of tests is in natconv_test.go)
	{"0b_1000/3", "8/3", true},
	{"0B_10_00/0x8", "1", true},
	{"0xdead/0B1101_1110_1010_1101", "1", true},
	{"0B1101_1110_1010_1101/0XD_E_A_D", "1", true},
	{"1_000.0", "1000", true},

	{"0x_10.0", "16", true},
	{"0x1_0.0", "16", true},
	{"0x1.8_0", "3/2", true},
	{"0X1.8p0_4", "24", true},
	{"0b1.1_0E2", "150", true},