code: func lexRightDelim(l *lexer) stateFn {
  	if l.doubleDelim && l.next() != '}' {
  		return l.errorf("expected double closing braces in tag")
  	}
  	l.emit(itemRightDelim)
  	return lexText
  }
docs: // lexRightDelim scans the right template tag delimiter
  // } has already been read.