magicbox.m:039: In `arguments_handler'(di, uo, out):
magicbox.m:039:   error: determinism declaration not satisfied.
magicbox.m:039:   Declared `cc_multi', inferred `cc_nondet'.
magicbox.m:056:   Call to `string.to_int'(in, out) can fail.
magicbox.m:062:   Call to `string.to_int'(in, out) can fail.