making it be a list of it

[DeaD_EyE]

You should look into the module typing.
It has a ABC for Iterators.
An Iterator is iterable, but not all iterables are iterators...

from typing import Iterator


x = list(it) if isinstance(it, Iterator) else [it]

If you want to check if the object is in iterator, you can use the built in iter function:

def gen():
    yield 42


a = gen()
b = gen()
c = [1]
d = [2]

iter(a) is iter(a) # True, it's the same iterator
iter(a) is iter(b) # False, we have two different Iterators
iter(c) is iter(c) # False, two different Iterators. A list object is not an Iterator, but it's iterable.
iter(c) is iter(d) # False, two different lists and two different Iterators

The objects c and d are lists (sequences) and not Iterators. They are iterable.
A iterator just knows the state during iteration.