Write a spell checker class that stores a set of words, W, in a
hash table and implements a function, spellCheck(s), which
performs a Spell Check on the string s with respect to the set of
words, W. If s is in W, then the call to spellCheck(s) returns an
iterable collection that contains only s, since it is assumed to be
spelled correctly in this case. Otherwise, if s is not in W, then
the call to spellCheck(s) returns a list of every word in W that
could be a correct spelling of s. Your program should be able to
handle all the common ways that s might be a misspelling of a
word in W, including swapping adjacent characters in a word ,
inserting a single character inbetween two adjacent characters
in a word, deleting a single character from a word, and
replacing a character in a word with another character. for an
extra challenge, consider phonetic substitutions as well