Draw a sequence diagram to illustrate the normal operation of the Use Case for "Change DVDs" for the DVD player described in the previous question.
Your sequence should start in the Playing state, and describe the scenario in which the user ejects the current disk, inserts a new one, and selects play again. Assume the DVD player software has to send signals to the motor (to tell it when to spin) and to the tray (to open and close), and in both cases needs to await confirmation from the device before doing anything else. Use activation bars to indicate when the devices are active. State any further assumptions you make.