DOMTokenList interface represents a set of space-separated tokens. Such a set is returned by
HTMLOutputElement.htmlFor. It is indexed beginning with
DOMTokenList is always case-sensitive.
Returns an item in the list by its index (returns undefined if the number is greater than or equal to the length of the list).
Replaces an existing token with a new token.
true if a given token is in the associated attribute's supported tokens.