unmark example

$this->assertTrue($marking->has('a'));
        $this->assertFalse($marking->has('b'));
        $this->assertSame(['a' => 1], $marking->getPlaces());

        $marking->mark('b');

        $this->assertTrue($marking->has('a'));
        $this->assertTrue($marking->has('b'));
        $this->assertSame(['a' => 1, 'b' => 1], $marking->getPlaces());

        $marking->unmark('a');

        $this->assertFalse($marking->has('a'));
        $this->assertTrue($marking->has('b'));
        $this->assertSame(['b' => 1], $marking->getPlaces());

        $marking->unmark('b');

        $this->assertFalse($marking->has('a'));
        $this->assertFalse($marking->has('b'));
        $this->assertSame([], $marking->getPlaces());
    }
}

$event = new LeaveEvent($subject, $marking, $transition, $this, $context);

            $this->dispatcher->dispatch($event, WorkflowEvents::LEAVE);
            $this->dispatcher->dispatch($event, sprintf('workflow.%s.leave', $this->name));

            foreach ($places as $place) {
                $this->dispatcher->dispatch($event, sprintf('workflow.%s.leave.%s', $this->name, $place));
            }
        }

        foreach ($places as $place) {
            $marking->unmark($place);
        }
    }

    private function transition(object $subject, Transition $transition, Marking $marking, array $context): array
    {
        if (!$this->shouldDispatchEvent(WorkflowEvents::TRANSITION, $context)) {
            return $context;
        }

        $event = new TransitionEvent($subject, $marking, $transition, $this, $context);