The ast-golf tag is a winning criterion where the program with the least AST nodes wins. This seems like a subset of atomic-code-golf, where the program with the least operations by some definition wins.
The following rules are typically enough to calculate the score of your program:
Block statements are 1 points: if, for ... in ..., while, else, etc.
Standalone statements are 1 point: print in Python 2, break, pass, etc.
Variables are 2 points
So, what should we do with ast-golf?