code: def get_library_value(self, key: str) -> typing.Any:
          
          desc = Metadata.session_key_map.get(key)
          if desc is not None:
              field_id = desc['path'][-1]
              return getattr(ApplicationData.get_session_metadata_model(), field_id)
          raise KeyError()
docs: Get the library value for the given key.
  
          Please consult the developer documentation for a list of valid keys.
  
          .. versionadded:: 1.0
  
          Scriptable: Yes