Invoking return through a function?

[Alberto Riva]

Hello,

I'm wondering if there is a way of writing a function that causes a 
return from the function that called it. To explain with an example, 
let's say that I want to exit my function if a dict does not contain a 
given key. I could write:

def testFun():
   ...
   if key not in dict:
     return
   ...

But if this is a test I need to do a lot of times, I'd like to replace 
it with something shorter and more explicit:

def testFun():
   ...
   checkKey(dict, key)
   ...

and I'd like checkKey to cause a return *from testFun*. In a language 
like Lisp this would be accomplished by defining checkKey as a macro 
that expands into the code shown in my first example, so that the return 
would be inside testFun and not insted checkKey. Is there a way of doing 
something like this in Python?

Another way of phrasing my question is: is there a way to cause a return 
from a function that is higher up in the call stack, rather than the 
currently active one, without using try/except?

Thanks,

Alberto
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