I used to have a children’s book in the 1970’s about a boy who gets a wooden box with a trick to open it and candy inside. He walks home with it and refuses to share the candy with another child, a dog and a person (Rule of three). He gets home and has forgotten how to open the box. He has to walk back to where he got the box, and this time he shares the candy on his way home and knows how to open the box to get the last piece himself when he gets home.