var u12 uint16 = 65535
	var u13 uint16 = +65535
	assert(u11 == u10+1, "u11")
	assert(u12 == u13, "u12")

	// uint32
	var u20 uint32 = 0
	var u21 uint32 = 1
	var u22 uint32 = 4294967295
	var u23 uint32 = +4294967295
	assert(u21 == u20+1, "u21")
	assert(u22 == u23, "u22")

	// uint64
	var u30 uint64 = 0
	var u31 uint64 = 1
	var u32 uint64 = 18446744073709551615