A good corrector prefers a close word over a far one, and only widens the search when it has to. Today you build Norvig's candidate ladder - known word, then one edit, then two, then give up - returning the first rung that has any real words.
Return the best available tier of candidates - the word itself, else one-edit words, else two-edit words, else the word alone.
Norvig’s corrector rests on a priority ladder: trust a small, near set of candidates over a large, far one. If the word is already spelled correctly, it is its own only candidate - no correction needed. Otherwise prefer the real words one edit away; only if there are none do you widen to two edits; and if even that is empty, fall back to the word itself (there is nothing better to offer).
This ordering encodes a simple, effective assumption: fewer edits means more likely. A one-edit neighbor almost always beats a two-edit one, whichever is more frequent, so distance is the outer sort and frequency (next lesson) only decides within the chosen tier. Returning the word itself as the last resort keeps the corrector total - it always returns something - so the document tool never has to handle a “no answer” case.
func (d *Dictionary) Candidates(word string) []string {// first non-empty of:// known word? -> [word]// known1(word) -> one-edit real words// known2(word) -> two-edit real words// fallback -> [word]}