* Return a css class for word that will be used with [ngClass] in order to (un-)highlight the word's rect.
*
* If a function has been passed to Input {@link #assignClass|assignClass},
* this function will call it if {@link #getHoverStatus|getHoverStatus(word)} == {@link /miscellaneous/enumerations.html#HIGHTLIGHT_CASES|HIGHTLIGHT_CASES.DEFAULT}.