Chaining calls to a class in Python

This is from a past programming contest

Implement a class Chain that when called a number of times in a chain with numeric inputs, returns the sum of them.

>>> Chain(1)(2)(3)
6
>>> Chain(10) == 10
True

The thing is that in the first example the first call should return a number (i.e. 1), which is not callable. So how can the chain continue evaluating?

>Solution :

You just need a callable int:

>>> class Chain(int):
...     def __call__(self, other: int) -> Chain:
...         return Chain(self + other)
...
>>> Chain(10) == 10
True
>>> Chain(1)(2)(3)
6