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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_all_handleable(self):
 """Get list of all known handleable devices."""

        nodes = self.get_device_tree()
        return [node.device
                for node in sorted(nodes.values(), key=DevNode._sort_key)
                if not node.ignored and node.device]