public boolean containsKey(long key) {

	    RBNode node = root;
        while(node != null) {
            if (key == node.key) {
                return true;
            }
            if (key < node.key) {
                node = node.left;
            }
            else {
                node = node.right;
            }
        }
        return false;
    }
Returns true if the key is in the set.
@param key the key whose presence is to be tested.
@exception IndexOutOfBoundsException thrown if the given key is not
in the range [0, maxKey].
Ghidra/Framework/Generic/src/main/java/ghidra/util/datastruct/RedBlackLongKeySet.java