buddhata: Great collection, but on the collection page it says this course has an average difficulty of 21k??? I think there is something wrong there...
TomaLexi: [current position] + M5
Regarding my previous comment, the solution is not yet present. The tree does not have this move in any variation.
M5 works as well, on top of M4.
TwT: You are right, the move is not present.
May you please give us the whole sequence as a proposal or SGF.
This move is slightly inferior. It is almost always better to squeeze one more liberty, but it works. I added it.