import ast
import builtins
import sys
import os

def log(msg, write=os.write):
    msg = (msg + "\n").encode()
    write(1, msg)

with open("func.py", encoding="ascii") as fp:
    source = fp.read()
tree = ast.parse(source)

class Cycle:
    def __del__(self):
        log("Cycle.__del__")
a = Cycle()
b = Cycle()
a.b = b
b.a = a
a.ast = tree

# Put the cycle somewhere to survive until the *last* GC collection
def callback(*args):
    pass
callback.a = a
os.register_at_fork(after_in_child=callback)

print("exit")