docs: def blocking_delete(self, meta=None, index_fields=None):
          """
          Deletes and waits till the backend properly update indexes for just deleted object.
          meta (dict): JSON serializable meta data for logging of save operation.
              {'lorem': 'ipsum', 'dolar': 5}
          index_fields (list): Tuple list for indexing keys in riak (with 'bin' or 'int').
              bin is used for string fields, int is used for integer fields.
              [('lorem','bin'),('dolar','int')]
          """
          self.delete(meta=meta, index_fields=index_fields)
          while self.objects.filter(key=self.key).count():
              time.sleep(0.3)