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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, *args, **kwargs):
 """Walks each step in the underlying graph, and raises an exception if any of the steps fail. Raises: PlanFailed: Raised if any of the steps fail. """

        self.walk(*args, **kwargs)

        failed_steps = [step for step in self.steps if step.status == FAILED]
        if failed_steps:
            raise PlanFailed(failed_steps)