* Update treap.py
check merge()
* Update treap.py
random() is used. its difficult to write doctests
l->left
r->right
key->value
add __repr__ and __str__ in preorder
* Wrote most of an rbt, missing just removal
* Added some convenience methods.
* Added a color method
* Wrote code to delete, but has issues :(
* Fixed a bug in Red-Black trees
* Fixed bug in tree color validation and delete repairing
* Clean up == comparison to None
* Added print function into matrix_multiplication_addition.py and removed blank space in data_structures/binary tree directory
* Removed .vs/ folder per #893
* Rename matrix_multiplication_addition.py to matrix_operation.py