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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 get_build_env(self):
 """Fetch the appropriate Environment to build this node. """

        try:
            return self._memo['get_build_env']
        except KeyError:
            pass
        result = self.get_executor().get_build_env()
        self._memo['get_build_env'] = result
        return result