func (w *SnowballWord) RemoveFirstSuffixIn(startPos int, suffixes ...string) (suffix string, suffixRunes []rune) {
	suffix, suffixRunes = w.FirstSuffixIn(startPos, len(w.RS), suffixes...)
	if suffix != "" {
		w.RemoveLastNRunes(len(suffixRunes))
	}
	return
}
func (w *SnowballWord) RemoveFirstSuffixIn(startPos int, suffixes ...string) (suffix string, suffixRunes []rune) {
	suffix, suffixRunes = w.FirstSuffixIn(startPos, len(w.RS), suffixes...)
	if suffix != "" {
		w.RemoveLastNRunes(len(suffixRunes))
	}
	return
}
// Removes the first suffix found that is in `word.RS[startPos:len(word.RS)]`