code: def add_batch(self, batch_id, batch_properties=None):
      
      if batch_properties is None:
        batch_properties = {}
      if not isinstance(batch_properties, dict):
        raise ValueError('batch_properties has to be dict, however it was: '
                         + str(type(batch_properties)))
      self._data[batch_id] = batch_properties.copy()
      self._data[batch_id]['images'] = {}
docs: Adds batch with give ID and list of properties.