public void ApplyCommandPlu100Minus50MutiplyBy10DividedBy2_Equal250()
        {
            User user = new User();

            // User presses calculator buttons
            user.Compute('+', 100);
            user.Compute('-', 50);
            user.Compute('*', 10);
            user.Compute('/', 2);

            Assert.Equal(250, user.GetResult());

            // Undo 4 commands
            user.Undo(4);

            Assert.Equal(0, user.GetResult());

            // Redo 3 commands
            user.Redo(3);

            Assert.Equal(500, user.GetResult());
        }