code: def create_empty_dataset(self, ds_name, dtype=np.float32):
          
          if ds_name in self._datasets:
              return self._datasets[ds_name]
  
          ds = self._group.create_dataset(ds_name, (1, 1), maxshape=None,
                                          dtype=dtype)
          self._datasets[ds_name] = ds
  
          return ds
docs: Creates a Dataset with unknown size.
          Resize it before using.
  
          :param ds_name: string
  
          :param dtype: dtype
          Datatype of the dataset
  
          :return: h5py DataSet