docs: def get_vocab(self, vocab_name, **kwargs):
          """ Returns data stream of an rdf vocabulary
  
          args:
              vocab_name: the name or uri of the vocab to return
          """
          vocab_dict = self.__get_vocab_dict__(vocab_name, **kwargs)
  
          filepaths = list(set([os.path.join(self.cache_dir,
                                             vocab_dict['filename']),
                                os.path.join(self.vocab_dir,
                                             vocab_dict['filename'])]))
          for path in filepaths:
              if os.path.exists(path):
                  with open(path, 'rb') as f_obj:
                      vocab_dict.update({"name": vocab_name,
                                         "data": f_obj.read(),
                                         "modified": os.path.getmtime(path)})
                  return vocab_dict
          download_locs = make_list(vocab_dict.get('download',[]))
          for loc in download_locs:
  
              loc_web = urllib.request.urlopen(loc)
              # loc_file_date = date_parse(loc_web.info()['Last-Modified'])
              urllib.request.urlretrieve(loc, filepaths[0])
              with open(filepaths[0], 'rb') as f_obj:
                  vocab_dict.update({"name": vocab_name,
                                     "data": f_obj.read(),
                                     "modified": os.path.getmtime(filepaths[0])})
                  return vocab_dict