Query for a subset of tasks by task_id.

        :param task_str:
        :return:

def task_search(self, task_str, **kwargs):
        """
        Query for a subset of tasks by task_id.

        :param task_str:
        :return:
        """
        self.prune()
        result = collections.defaultdict(dict)
        for task in self._state.get_active_tasks():
            if task.id.find(task_str) != -1:
                serialized = self._serialize_task(task.id, include_deps=False)
                result[task.status][task.id] = serialized
        return result