interrupt_yield_2.py

interrupt_handler = lambda _: None

def foo():
    global interrupt_handler
    # also could be something like write to a channel, opened only locally in foo
    def h(x):
        print(x)

    interrupt_handler = h
    for i in bar():
        print(i)

def bar():
  yield 4
  yield 3
  baz()
  yield 1

def baz():
  # somehow force bar to `yield`
  # or `return` 2
    interrupt_handler(2)

print(foo())