Package tree23 is an implementation for a balanced 2-3-tree. It distinguishes itself from other implementations of 2-3-trees by having a few more functions defined for finding elements close to a key (similar to possible insert positions in the tree) for floating point keys and by having a native function to retrieve the next or previous leaf element in the tree without knowing its key or position in the tree that work in O(1) for every leaf! The last element links to the first and the first back to the last element. The tree has its own memory manager to avoid frequent allocations for single nodes that are created or removed.