code: def get_all_handleable_roots(self):
          
          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
                  and (node.root == '/' or nodes[node.root].ignored)]
docs: Get list of all handleable devices, return only those that represent
          root nodes within the filtered device tree.