code: def raw(self, use_local=True):
          
          if use_local and self.is_local:
              return pkgutil.get_data('vega_datasets', self.pkg_filename)
          else:
              return urlopen(self.url).read()
docs: Load the raw dataset from remote URL or local file
  
          Parameters
          ----------
          use_local : boolean
              If True (default), then attempt to load the dataset locally. If
              False or if the dataset is not available locally, then load the
              data from an external URL.