Extend BSTreeMap with another class called RBTreeMap. The red$-$black tree is a balanced binary search tree. It is comprised of RBNodes. The RBTreeMap and RBNode classes are shown in the attachment.

Use the files provided to get started $($RBTreeMap$.$java, RBNode.java$).$ Test your work with JUnit test cases. It is up to you to test your work thoroughly.

A fully working remove method is important. It must at least pass testRemove$01()$ supplied in the JUnit file.

Create a zip file with just RBTreeMap.java inside, not any other files. Of course, that means that you cannot change anything in those other classes.