go2:
    go 2
    d 1
nested_go2:
    go 2
    go2 2
    d 1
    n 1
d0:
    go 1
    d 0
go2 (in case crut):
    go 2
    d 1
go2 (in function call):
    go 2
    d 1
go2 (using surrounding interesting let):
    go 2
    d 1
    n 1
go2 (using surrounding boring let):
    go 2
    d 1
    z 0
two recursions (both arity 1 would be good!):
    d 0
    n 1
two recursions (semantically like the previous case):
    d 1
    n 1
two thunks, one called multiple times (both arity 1 would be bad!):
    d 0
    n 1
two thunks (recursive), one called multiple times (both arity 1 would be bad!):
    d 0
    n 1
two functions, not thunks:
    go 2
    go2 2
a thunk, called multiple times via a forking recursion (d 1 would be bad!):
    go2 2
    d 0
a function, one called multiple times via a forking recursion:
    go 2
    go2 2
two functions (recursive):
    go 2
    go2 2
mutual recursion (thunks), called mutiple times (both arity 1 would be bad!):
    d 0
    n 0
mutual recursion (functions), but no thunks:
    go 2
    go2 2
mutual recursion (functions), one boring (d 1 would be bad):
    go 0
    go2 2
    d 0