Write-only set interface (the set cannot be queried, but items can be added to it.) Note: BTree<K,V> does not officially implement this interface, but BTree can be used as an instance of ISetSink.
Adds the specified item to the set, if it was not in the set already.
Removes everything so that the set is empty.
Returns true if an element in the map object existed and has been removed, or false if the element did not exist.
Write-only set interface (the set cannot be queried, but items can be added to it.) Note: BTree<K,V> does not officially implement this interface, but BTree
can be used as an instance of ISetSink.