Help Solve This Picture Puzzle Please .....

[Gizmonster]

So this has come up on my FB memories ..... unfortunately I can't find the answer and it's doing my nut in:

https://photos.google.com/share/AF1QipMSQVymYosQ4BPhlL9ROO_ds-fqY3U6SdTXzTAtIXZZLTnbUWVekKkMDV3Jwyvh6Q/photo/AF1QipPu295fyfw__LsZqyxzooC88AsFD9bHEyy93xUp?key=VEFkOG5OdTdtcm81aS1wOWZhTHJneTRZalE5S1JB

Help please before my head explodes .....

[Gizmonster]

C'mon peeps .... get your thinking caps on.

The answer is in my head somewhere ..... I can kinda remember the solution ..... it's not a straight forward cut. The cut goes up and down and diagonally several times, like the teeth of a saw .... but the actual solution still eludes me .....

[Etch]

Something like this (sorry for the poor quality):
https://postimg.cc/rKg01K9V

[Gizmonster]

That's the one.
You just slide the upper piece up slightly and to the left, then slot it back in to form a 10 x 10 square - cheers :)