insert

>>-insert(item-+--------+-)------------------------------------><
               +-,index-+

Returns a collection-supplied index for item [item] , which is added to the collection. The inserted item follows an existing item with index [index] in the collection ordering. If [index] is the Nil object, [item] becomes the first item in the ordered collection. If you omit [index] , the [item] becomes the last item in the collection.

Inserting an item in the collection at position [index] will cause the items in the collection after position [index] to have their relative positions shifted by the collection object. Depending on the nature of the collection, the index values for any items already in the collection may be modified by the insertion.

This is an abstract method that must be implemented by a subclass of this class.