:@choice = 2

:f = "f"!script($_)
	*| a
		|-> a
		#p!checkpoint
		*| aa
			|-> aa
		*| ab
			|-> ab
	*| b
		|-> b
	choice = 2

	*| c
		|-> c
	choice=1

| f:
f!

| f from #p:
f!from(#p)