'Schedules this task.
See Scheduler.schedule() and Scheduler.fast_schedule() for the meaning
of the \'fast\' argument.'

def start(self, scheduler=None, priority=None, fast=False):

    if (scheduler is None):
        scheduler = defaultScheduler
    if (priority != None):
        self.priority = priority
    if fast:
        scheduler.fast_schedule(self)
    else:
        scheduler.schedule(self)
