docs: def load(self, modelfile, layer=None):
          """
          Load or update a model or layers in a model.
  
          :param modelfile: The name of the json file to load.
          :type modelfile: str
          :param layer: Optionally load only specified layer.
          :type layer: str
          """
          # read modelfile, convert JSON and load/update model
          self.param_file = modelfile
          self._load(layer)
          self._update(layer)