Another case:

model="Hello"
class M(object):
    def __init__(self):
        pass
    def __call__(self):
        print(self.model)

cvs = inspect.getclosurevars(M.__call__)

ClosureVars(nonlocals={}, globals={'model': 'Hello'}, builtins={'print': <built-in function print>}, unbound=set())

Of course self.model does not refer to the global model
M()()
AttributeError: 'M' object has no attribute 'model'