def _load(self):
        """Entry point from __init__ to load the dataset.

        If cache exists:

          - Load the dataset from saved dgl graph and information files.
          - If loadin process fails, re-download and process the dataset.

        else:

          - Download the dataset if needed.
          - Process the dataset and build the dgl graph.
          - Save the processed dataset into files.
        """
        load_flag = not self._force_reload and self.has_cache()

        if load_flag:
            try:
                self.load()
                if self.verbose:
                    print("Done loading data from cached files.")
            except KeyboardInterrupt:
                raise
            except:
                load_flag = False
                if self.verbose:
                    print(traceback.format_exc())
                    print("Loading from cache failed, re-processing.")

        if not load_flag:
            self._download()
            self.process()
            self.save()
            if self.verbose:
                print("Done saving data into cached files.")
Entry point from __init__ to load the dataset.

        If cache exists:

          - Load the dataset from saved dgl graph and information files.
          - If loadin process fails, re-download and process the dataset.

        else:

          - Download the dataset if needed.
          - Process the dataset and build the dgl graph.
          - Save the processed dataset into files.
        
python/dgl/data/dgl_dataset.py