World's Easiest Jigsaw Puzzle - or is it?!

This looks like the world's easiest jigsaw puzzle - just four identical pieces! However, assembling the puzzle is trickier than it looks - and getting it apart again can also be a challenge!

Print 4 pieces, and then try to join them together - yes, they will fit, without requiring any forcing. Disassembly is simply the reverse of the procedure required to fit them together.

SPOILER ALERT:
The solution can be found here https://www.cs.brandeis.edu/~storer/JimPuzzles/ZPAGES/zzzJigSawFourPiece.html - but do yourself a favour, and try to solve the puzzle before you download the solution!
(Note: Unlike the puzzle shown in the solution sheet, all four pieces of my puzzle are identical, and the puzzle can be assembled with the four pieces in any order.)