action is still supported, as well as function. They are just definitions of void. But it can't hurt to replace them, I'd recommend it as well
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Since you use a vector pointer instead of a vector, you need to write temp_b->x, temp_b->y etc.
The app crashes because boosterpaal is probably not assigned to rotate_boosterarm yet. You need to let the function wait for the entity to be assigned by writing:
while(!boosterpaal){wait(1);}above in the function.
