String (String verb) { String irregularVerb = IRREGULAR_VERBS.get(verb); if (irregularVerb != null) return irregularVerb; for (String prefix : PREFIXES) { if (verb.startsWith(prefix)) { irregularVerb = IRREGULAR_VERBS.get(verb.substring(prefix.length())); if (irregularVerb != null) return prefix + irregularVerb; } } return null; }