Added support for delayed deferred with no value

ipv8/attestation/trustchain/caches.py

@@ -107,7 +107,7 @@ def on_timeout(self):
         if self.timeouts < 360:
             self.community.send_block(self.half_block, address=self.socket_address)
 
-            def add_later():
+            def add_later(_):
                 self.community.request_cache.add(HalfBlockSignCache(self.community, self.half_block, self.sign_deferred,
                                                                     self.socket_address, self.timeouts + 1))
             later = Deferred()

ipv8/taskmanager.py

@@ -54,8 +54,6 @@ def register_task(self, name, task, delay=None, value=None, interval=None):
 
             if delay is not None:
                 if isinstance(task, Deferred):
-                    if value is None:
-                        raise ValueError("Expecting value to fire the Deferred with")
                     dc = self._reactor.callLater(delay, task.callback, value)
                 elif isinstance(task, LoopingCall):
                     if interval is None:

ipv8/test/test_taskmanager.py

@@ -56,9 +56,6 @@ def test_looping_call_and_cancel(self):
     def test_delayed_looping_call_requires_interval(self):
         self.assertRaises(ValueError, self.tm.register_task, "test", LoopingCall(lambda: None), delay=1)
 
-    def test_delayed_deferred_requires_value(self):
-        self.assertRaises(ValueError, self.tm.register_task, "test", deferLater(reactor, 0.0, lambda: None), delay=1)
-
     def test_delayed_looping_call_requires_LoopingCall_or_Deferred(self):
         self.assertRaises(ValueError, self.tm.register_task, "test not Deferred nor LoopingCall",
                           self.tm._reactor.callLater(0, lambda: None), delay=1)