var source = func() []byte {
	var src []byte
	for _, t := range tokens {
		src = append(src, t.lit...)
		src = append(src, whitespace...)
	}
	return src
}()

func newlineCount(s string) int {
	n := 0
	for i := 0; i < len(s); i++ {
		if s[i] == '\n' {
			n++
		}
	}
	return n
}

func checkPos(t *testing.T, lit string, p token.Pos, expected token.Position) {