For the current implementation, the constant of proportionality is eight words per association. Red-black trees hold their keys strongly . In other words, if a red-black tree contains an association for a given key, that key cannot be reclaimed by the garbage collector. This procedure creates and returns a newly allocated red-black tree. For any two keys, at most one of these predicates is true.
Associates datum with key in rb-tree and returns an unspecified value.
If rb-tree already has an association for key , that association is replaced. If rb-tree doesn't contain an association for key , default is returned. If rb-tree contains an association for key , removes it. Returns an unspecified value. The time required by this operation is proportional to the number of associations in the tree.