promql/lex.go
func lexLineComment(l *lexer) stateFn {
	l.pos += Pos(len(lineComment))
	for r := l.next(); !isEndOfLine(r) && r != eof; {
		r = l.next()
	}
	l.backup()
	l.emit(ItemComment)
	return lexStatements
}
func lexLineComment(l *lexer) stateFn {
	l.pos += Pos(len(lineComment))
	for r := l.next(); !isEndOfLine(r) && r != eof; {
		r = l.next()
	}
	l.backup()
	l.emit(ItemComment)
	return lexStatements
}
// lexLineComment scans a line comment. Left comment marker is known to be present.