Is nested function a good approach when required by only one function? [closed]

>>> def sum(x, y):
...     def do_it():
...             return x + y
...     return do_it
... 
>>> a = sum(1, 3)
>>> a
<function do_it at 0xb772b304>
>>> a()
4

Is this what you were looking for? It’s called a closure.