def test_negative_scalar_index(adata, index: int, obs: bool):
    pos_index = index + (adata.n_obs if obs else adata.n_vars)

    if obs:
        adata_pos_subset = adata[pos_index]
        adata_neg_subset = adata[index]
    else:
        adata_pos_subset = adata[:, pos_index]
        adata_neg_subset = adata[:, index]

    np.testing.assert_array_equal(
        adata_pos_subset.obs_names, adata_neg_subset.obs_names
    )
    np.testing.assert_array_equal(
        adata_pos_subset.var_names, adata_neg_subset.var_names
    )
def on_backend_added(self, sender, backend_id):
        """
        Signal callback executed when a new backend is loaded

        @param sender: not used, only here to let this function be used as a
                       callback
        @param backend_id: the id of the backend to add
        """
        # Add
        backend = self.req.get_backend(backend_id)
        if not backend:
            return
        self.add_backend(backend)
        self.refresh()
        # Select
        self.select_backend(backend_id)
        # Update it's enabled state
        self.on_backend_state_changed(None, backend.get_id())