Prepare watchdog for scheduled task starting

		:return: None

def __dog_started(self):
		""" Prepare watchdog for scheduled task starting

		:return: None
		"""
		if self.__task is not None:
			raise RuntimeError('Unable to start task. In order to start a new task - at first stop it')

		self.__task = self.record().task()
		if isinstance(self.__task, WScheduleTask) is False:
			task_class = self.__task.__class__.__qualname__
			raise RuntimeError('Unable to start unknown type of task: %s' % task_class)