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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def execute(self):
 """Run all child tasks, in order, waiting for completion of each. Return the result of the final child task's execution. """

        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