code: def _vector_layers(self):
          
          layers = []
          vector_datasource = self.vector_driver.Open(
              self.uri.absoluteFilePath())
          if vector_datasource:
              for i in range(vector_datasource.GetLayerCount()):
                  layers.append(vector_datasource.GetLayer(i).GetName())
          return layers
docs: Return a list of vector layers available.
  
          :return: List of vector layers available in the geopackage.
          :rtype: list
  
          .. versionadded:: 4.0