...
PuzzleState current = problem.getCurrentState();
PuzzleState newState = move.doMove(current);
if ( newState == null ) {
display("That move is not possible. Try again.\n");
}
else {
problem.setCurrentState(newState);
display(newState.toString());
}
...
Draw a sequence diagram that describes the code segment. Assume that console, problem, current, and move exist when the sequence begins. Also assume that the created newState is not null.