Write a function called elfish that recursively checks, given a word, if that word is elfish or not. bool elfish(char *word, c har *elf, int index) A word is considered elfish if it contains the letters: e, l, and f in it, in any order. For example, we would say that the following words are elfish: white leaf, tasteful, unfriendly, and waffles, because they each contain those letters.