\ Btree of BtSet's vandys
only extensions definitions
Btree -> subclass: BtBtSet
BtBtSet -> :method ! ( ... self -- ) 1 abort" Bad API use" method;
BtBtSet -> :method @ { key self -- btset }
key self super-> @ if exit then
BtSet -> new dup { btset } key self super-> ! btset method;
BtBtSet -> :method in? ( key self -- ? )
super-> @ dup if nip then method;
Basically a Btree whose leaves are of a specific type
Can't store nodes directly
:method @ Return a BtSet for the key, creating one on 1st reference
:method in? Tell if a given key is in the BtBtSet