code: def test_promise_follows_indifentely():
      a = Promise.resolve(None)
      b = a.then(lambda x: Promise.resolve("X"))
      e = Event()
  
      def b_then(v):
          c = Promise.resolve(None)
          d = c.then(lambda v: Promise.resolve("B"))
          return d
  
      promise = b.then(b_then)
  
      assert promise.get() == "B"
  
imports: from promise import Promise
  from .utils import assert_exception
  from threading import Event
label_desc: Use image node_id 27 for calling a global function with example usage: test_promise_follows_indifentely() and returns: d