from typing import Callable

class SomeClass(object):
    def __init__(self): #type: (SomeClass) -> None
        self.x=set() # type: Set[Callable]
        self.mx=set() #type: Set[int]
        
    def fn(self, *a): #type: (SomeClass, *Callable) -> None
        if not len(a):
            a=(tuple(self.x) + tuple(self.mx))