You mean: def myfunc(): try: while x in someiterator(): a = x dosomethingwith(a) except: # Does a exist here or not? I

You mean: def myfunc(): try: while x in someiterator(): a = x dosomethingwith(a) except: # Does a exist here or not? If someiterator() raises then a won't exist in the function block. Otherwise it will.