func (s LexSymbolSorter) Less(i, j int) bool {
	return s.list[i].Priority > s.list[j].Priority
}
func (s LexSymbolSorter) Less(i, j int) bool {
	return s.list[i].Priority > s.list[j].Priority
}
// Less returns true if the i-th element's Priority is less than the j-th element