func (l *lexer) linePosition() int {
	lb := strings.LastIndex(l.input[:l.lastPos], "\n")
	if lb == -1 {
		return 1 + int(l.lastPos)
	}
	return 1 + int(l.lastPos) - lb
}
func (l *lexer) linePosition() int {
	lb := strings.LastIndex(l.input[:l.lastPos], "\n")
	if lb == -1 {
		return 1 + int(l.lastPos)
	}
	return 1 + int(l.lastPos) - lb
}
// linePosition reports at which character in the current line
// we are on.