The element at index has been removed and replaced by nil.
This method moves forward from there, relocating any entries
that had been placed below due to collisions with this one
Scan the key array for the first slot containing either a nil (indicating an empty slot) or an element that matches anObject. Answer the index of that slot or zero if no slot is found. This method will be overridden in various subclasses that have different interpretations for matching elements
Remove oldObject from the receiver's elements. If several of the
elements are equal to oldObject, only one is removed. If no element is
equal to oldObject, answer the result of evaluating anExceptionBlock.
Otherwise, answer the argument, oldObject. ArrayedCollections cannot
respond to this message.