:param predicate: optional callable that must take as an
argument a delta, and must return a boolean, indicating
whether the delta contains the specific action we're looking
:param predicate: optional callable that must take as an
argument a delta, and must return a boolean, indicating
whether the delta contains the specific action we're looking
self.add_observer(callback, entity_type, action, entity_id, predicate)
entity_id = await q.get()
self.add_observer(callback, entity_type, action, entity_id, predicate)
entity_id = await q.get()
async def _wait_for_new(self, entity_type, entity_id=None, predicate=None):
"""Wait for a new object to appear in the Model and return it.
async def _wait_for_new(self, entity_type, entity_id=None, predicate=None):
"""Wait for a new object to appear in the Model and return it.