The Final Step
There is a game that many of us play which involves in joining the pieces together. This makes a picture or something like that when the pieces are connected together in a perfect order. For a game like this to end, the availability of all pieces is essential so that the picture gets completed.

Imagine what will happen if you finish the entire picture except for one piece that has been lost. In this instance, the pieces are making a picture of the taxi cab and it seems that the person connecting it has almost finished it. There is one piece that remains lost hence making the picture incomplete.