@contextmanager
def nested(*managers):
    'Nest context managers.'
    exits = []
    vars = []
    exc = (None, None, None)
    try:
        try:
            for mgr in managers:
                exit = mgr.__exit__
                enter = mgr.__enter__
                vars.append(enter())
                exits.append(exit)
            (yield vars)
        except:
            exc = sys.exc_info()
        finally:
            while exits:
                exit = exits.pop()
                try:
                    if exit(*exc):
                        exc = (None, None, None)
                except:
                    exc = sys.exc_info()
            if (exc != (None, None, None)):
                reraise(exc[0], exc[1], exc[2])
    finally:
        del exc
Nest context managers.
@contextmanager
def nested(*managers):
    
    exits = []
    vars = []
    exc = (None, None, None)
    try:
        try:
            for mgr in managers:
                exit = mgr.__exit__
                enter = mgr.__enter__
                vars.append(enter())
                exits.append(exit)
            (yield vars)
        except:
            exc = sys.exc_info()
        finally:
            while exits:
                exit = exits.pop()
                try:
                    if exit(*exc):
                        exc = (None, None, None)
                except:
                    exc = sys.exc_info()
            if (exc != (None, None, None)):
                reraise(exc[0], exc[1], exc[2])
    finally:
        del exc