That was helpful for me too. I also found Flexy Boxes to be useful: http://the-echoplex.net/flexyboxes/

This one from Philip Walton is quite handy too: https://philipwalton.github.io/solved-by-flexbox/ (The six examples in the showcase are all very common problems, and well-solved with Flexbox.)

yeah this is my go to when I can't remember some little part of the flex box spec.