code: def gather_registries() -> Tuple[Dict, Mapping, Mapping]:
      
      id2devices = copy.copy(_id2devices)
      registry = copy.copy(_registry)
      selection = copy.copy(_selection)
      dict_ = globals()
      dict_['_id2devices'] = {}
      dict_['_registry'] = {Node: {}, Element: {}}
      dict_['_selection'] = {Node: {}, Element: {}}
      return id2devices, registry, selection
docs: Get and clear the current |Node| and |Element| registries.
  
      Function |gather_registries| is thought to be used by class |Tester| only.