code: def reverse(self):
          
          self.left_motor.value = -self.left_motor.value
          self.right_motor.value = -self.right_motor.value
docs: Reverse the robot's current motor directions. If the robot is currently
          running full speed forward, it will run full speed backward. If the
          robot is turning left at half-speed, it will turn right at half-speed.
          If the robot is currently stopped it will remain stopped.