Data stores must subclass these cursor classes and implement all the methods described in DSR Cursors except Macro elephant:with-btree-cursor.
Predicate indicating whether the btree in question is initialized or not. Initialized means that the cursor has a legitimate position, not that any initialization action has been taken. The implementors of this abstract class should make sure that happens under the sheets... Cursors are initialized when you invoke an operation that sets them to something (such as cursor-first), and are uninitialized if you move them in such a way that they no longer have a legimtimate value.
A cursor for traversing (primary) BTrees.