code: def execute(self):
          
          while self.index < len(self.tasklist):
              res = self.step()
              self.logger.debug('SeqSet task %i has completed with result %s' %
                                (self.index, res))
  
          # Returns result of last task to quit
          return res
docs: Run all child tasks, in order, waiting for completion of each.
          Return the result of the final child task's execution.