The return status of tasks is currently a three-state :

• Exception => the task failed
• True => the task succeeded and did something
• False => the task succeeded and did nothing

We need to extend the return values to allow tasks to return a partial state.

One possible return value could be a dict with multiple values :

• completion: full/partial
• eventful: True/False
• state: variable to pass to the next partial task run
• delay: the delay before reexecution of a partial loading task