I was reading some python code and come across this. Since I mostly write C and Java (And variable as statement doesn't even compile in these language) I'm not sure what it is about in python.
self.queue = 
self.current = 0
if self.current >=len(self.queue):
out = self.queue[self.current]
self.current += 1
It really doesn't do anything, the only way it can do anything in particular, as @Daniel said in the comments, is if
self.current refers to a property method. Something like the following:
class X(): @property def current(self): mail_admins() return whatever def next(self): ...
This way, calling
self.current, would actually do something.
But anyways its definitely not considered good practice since a property is just that, a property, if it's supposed to do something, it should be method.