Update @particle_input to handle typing that utilzes Union[], List[], etc.

@particle_input ques off of arguments annotated with Particle to properly condition that argument into a Particle() object. However, that argument is allowed to be a string (e.g. "He+") or a Particle() object and, thus, should really be annotated with Union[str, Particle]. Without this annotation, IDEs will generally throw warnings if you trying to use "He+" as an argument.

I think @particle_input can accomplish this by doing something like...

def find_particle(func):
     def find_in_depth(args):
         for arg in args:
             if hasattr(arg, "__args__"):
                 result = find_in_depth(arg.__args__)
             else:
                 result = Particle == arg
             
             if result:
                 break
 
         return result
 
     annos = func.__annotations__
     found = {}
 
     for name, anno in annos.items():
         if hasattr(anno, "__args__"):
             results = find_in_depth(anno.__args__)
         else:
             results = Particle == anno

         found[name] = results

     return found

Then the following would result in...

>>> def foo(ion: Union[str, Particle], par: Particle, p2: List[Particle], arg: [u.cm, u.kg]):
...     pass
>>> find_particle(foo)
{'ion': True, 'par': True, 'p2': True, 'arg': False}