Put together binary search tree code in C++ and use a test driver to perform some operations such as insert, erase, and find.

Assume that key is an integer and value is a string. Duplicate keys are allowed.

Provide the final BST after the following operations (showing keys only).

1. Insert 10

2. Insert 20

3. Insert 4

4. Insert 8

5. Insert 15

6. Insert 20

7. Erase 8

8. Erase 10

Also for question 2: Outline the steps to remove a node in a BST.