code: def then(self, s=None, f=None):
      if self.raises:
          raise Exception("FakeThenPromise raises in 'then'")
  
imports: from time import sleep
  from pytest import raises, fixture
  from threading import Event
  from promise import Promise, is_thenable, promisify, promise_for_dict
  from concurrent.futures import Future
  from threading import Thread
  from .utils import assert_exception
label_desc: Use image node_id 2 for calling the FakeThenPromise obj's underlying member method code with example usage: obj.then(s, f) without return types