func lexCommentStart(l *Lexer) stateFn {
	l.emit(LexemeComment)
	return lexComment
}
lexCommentStart scans a comment delimiter. the Left comment Lexeme is known to be present.
package lexer
import (
	"strconv"
	"unicode"
)
type stateFn func(*Lexer) stateFn
func lex(l *Lexer) stateFn {
	l.stripWhitespace()
	switch {
	case l.isEmpty():
		if !l.emptyStack() {
			return l.pop()
		}
		l.emitSynthetic(LexemeEOF, "")
		return nil
	case l.consumedWhitespaced(golangComment, yamlComment):
		return lexCommentStart
	case l.consumed(markerStart):
		return lexMarkerStart
	default:
		l.discard()
		return lex
	}
}