> a ~ 1
	-> a
> b
	-> b
~ choose(1)

> a ~ 1
	-> a
> b
	-> b
~ choose(2)

> a ~ 0
	-> a
> b
	-> b
~ choose(1)

> a
	-> a
> b # 25
	-> b
~ choose(2)

> a ~ 0 # 12
	-> a
> b # 3
	-> b
~ choose(1)

> a ~ 1 # 12
	-> a
> b # 3
	-> b
~ choose(1)