Insert adds key to the tree and associates key with data. If key was already in the tree, it updates the associated data. Insert returns the previous data associated with key, or nil if key was not present. Insert panics if data is nil.
} t.Insert(d, sstring(fmt.Sprintf("%v", d))) k++ s, i := t.wellFormed()
right := blockIndex.exit - adjust _ = rbtree.Insert(right, entry) left := blockIndex.entry + adjust
left := blockIndex.entry + adjust _ = rbtree.Insert(left, entry) // This newly inserted block may now be the sparse parent of some existing nodes (the new sparse children of this block)