Remove the bridge pin to free the other side of the string.

Sometimes, you need to take the picture slightly differently than you would actually perform the task. Some things are impossible to show the actual action.

Removing a bridge pin takes some force wiggling back and forth, which you can't show in a picture. In this case, we removed the pin ahead of time, then put it back for the picture.

It's more important to show the 'goal' of the shot than the actual action. In this case, pulling the pin partially out shows the viewer what the complete pin looks like, even though the task is essentially complete by the time the photo is taken.

Make sure that your hand (or any other object) does not interfere with the action being performed.