insane_python.py

def main():
  raiseEx = True
  returnA = True
  returnB = True
  try: #A
    try: #B
      if raiseEx:
        raise OSError()
      return 3
    finally: #B
      print("B1")
      if returnB:
        return 2
      print("B2")
  except OSError as e: #A
    print("catch")
  finally: #A
    print("A1")
    if returnA:
      return 1
    print("A2")

print(main())