:@choice = 1
:i = "i"!script($_)
	*| a
		|-> a
		#p!checkpoint
		*| aa
			|-> aa
		*| ab
			|-> ab
	*| b
		|-> b
	if(1)
		*| c
			|-> c

| i:
i!

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