def show_attrs(key, calc_id=-1):
    """
    Show the attributes of a HDF5 dataset in the datastore.
    """
    ds = util.read(calc_id)
    try:
        attrs = h5py.File.__getitem__(ds.hdf5, key).attrs
    except KeyError:
        print('%r is not in %s' % (key, ds))
    else:
        if len(attrs) == 0:
            print('%s has no attributes' % key)
        for name, value in attrs.items():
            print(name, value)
    finally:
        ds.close()
Show the attributes of a HDF5 dataset in the datastore.