code: def update_file(self, filepath, df, notes=None):
          
          assert isinstance(df, pd.DataFrame), "Cannot update file with type '{}'".format(type(df))
  
          self._models[filepath].setDataFrame(df, copyDataFrame=False)
  
          if notes:
              update = dict(date=pd.Timestamp(datetime.datetime.now()),
                                                       notes=notes)
  
              self._updates[filepath].append(update)
          self._paths_updated.append(filepath)
docs: Sets a new DataFrame for the DataFrameModel registered to filepath.
          :param filepath (str)
              The filepath to the DataFrameModel to be updated
          :param df (pandas.DataFrame)
              The new DataFrame to register to the model.
  
          :param notes (str, default None)
              Optional notes to register along with the update.