> {} (or what we'll call `None` or `Nothing`) if there is no object that E refers to, or else
> {P} (or what we'll call `Some P` or `Just P`) if E refers to P
> {} (or what we'll call `None` or `Nothing`) if there is no object that E refers to, or else
> {P} (or what we'll call `Some P` or `Just P`) if E refers to P