"<a href=""https://www.youtube.com/watch?v=KN2TTiGpDvM&amp;t=1m20s"">1:20</a> but you are wrong: this doesn't return 42. It returns a reference to X", which is equal to 42 in this case,(reply>), It doesn't return a reference to `x`; it returns a copy of the same reference `x` has. If either value is mutated (e.g. list.append; not possible with `int`s), the both are affected. If one of them is re-assigned, they become references to different values. cc @Hamza Hajji,(reply>), what if I assigned it a y, and changed y later in the code?