Question

def foo(self, sub, **kwargs):
    accounts = kwargs.get('accounts')        
    start    = kwargs.get('start', 0)        
    end      = kwargs.get('end', 0)          
    return json.dumps(                       
        sub(accounts, start, end),           
    ) 

Can you explain, what this ‘sub’ is and what it does?

Answer 1

It’s just a parameter of the function, and the code expects it to be a callable.

Python functions, methods and objects with a __call__ method are all callable and could be used to supply foo with an argument sub.

There is not much else we can say about this without a lot more context.