passing parameters to the method passed to Dataset.from_generator()
Hi! Yes, you can either use the `gen_kwargs` param in `Dataset.from_generator` (`ds = Dataset.from_generator(gen, gen_kwargs={"param1": val})`) or wrap the generator function with `functools.partial`
(`ds = Dataset.from_generator(functools.partial(gen, param1="val"))`) to pass custom parameters to it.

Big thanks for providing dataset creation via a generator.
I want to ask whether there is any way that parameters can be passed to the method Dataset.from_generator() method, like as follows. 

```
from datasets import Dataset

def gen(param1):
    for idx in len(custom_dataset):
        yield custom_dataset[idx] + param1

ds = Dataset.from_generator(gen(param1))
```
