code: def write_fc3_to_hdf5(fc3,
                        filename='fc3.hdf5',
                        p2s_map=None,
                        compression=None):
      
  
      with h5py.File(filename, 'w') as w:
          w.create_dataset('fc3', data=fc3, compression=compression)
          if p2s_map is not None:
              w.create_dataset('p2s_map', data=p2s_map)
docs: Write third-order force constants in hdf5 format.
  
      Parameters
      ----------
      force_constants : ndarray
          Force constants
          shape=(n_satom, n_satom, n_satom, 3, 3, 3) or
          (n_patom, n_satom, n_satom,3,3,3), dtype=double
      filename : str
          Filename to be used.
      p2s_map : ndarray, optional
          Primitive atom indices in supercell index system
          shape=(n_patom,), dtype=intc
      compression : str or int, optional
          h5py's lossless compression filters (e.g., "gzip", "lzf").
          See the detail at docstring of h5py.Group.create_dataset. Default is
          None.