### getting RESetMapReduce to use multiple cores

I am reading the documentation on how to parallelize recursive-enumeration computations, and I cannot for the life of me get `RESetMapReduce`

to use more than one core of my machine.

I am using the example immediately before the bulleted item titled **Generating series** on that page, with a minor modification:

```
sage: from sage.parallel.map_reduce import RESetMapReduce
sage: S = RESetMapReduce(
....: roots=[[]],
....: children=lambda l: [l + [0], l + [1]] if len(l) < 32 else [],
....: map_function=lambda x: 1,
....: reduce_function=lambda x, y: x + y,
....: reduce_init=0)
sage: S.run()
```

I changed the length to 32 to make the computation heftier. If I run this, I can watch the process with `htop`

~~, using ~~: it uses only one of my 8 cores to `100%`

capacity, ~~but ~~ignoring the others.

I have even tried passing the argument `max_proc=8`

to the `.run()`

method, to no effect.