Sorry, We're Clopen.

clopen.py

Python 3.6.4 (default, Mar 23 2018, 08:00:10) 
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def opencell_gen(i):
...     a = i
...     def f(b):
...         b = a
...     a = yield f.__closure__[0]
...     while True:
...         a = yield None
... 
>>> def replace_cells(f, cells):
...     return type(f)(
...         f.__code__,
...         f.__globals__,
...         f.__name__,
...         f.__defaults__,
...         cells
...     )
... 
>>> def make_adder(x):
...     """Make a simple closure"""
...     def add(y):
...         return x + y
...     return add
... 
>>> adder = make_adder(1)
>>> adder(2)
3
>>> controller = opencell_gen(5)
>>> opencell = next(controller)
>>> adder = replace_cells(adder, (opencell,))
>>> adder(2)
7
>>> controller.send(10)
>>> adder(5)
15
>>> controller.send(20)
>>> adder(5)
25