def METHOD_NAME(
    staff_api_client, checkout, permission_manage_checkouts
):
    # given
    checkout.metadata_storage.store_value_in_private_metadata(
        {PRIVATE_KEY: PRIVATE_VALUE, "to_clear": PRIVATE_VALUE},
    )
    checkout.metadata_storage.save(update_fields=["private_metadata"])
    checkout_id = graphene.Node.to_global_id("Checkout", checkout.pk)
    # when
    response = execute_clear_private_metadata_for_item(
        staff_api_client,
        permission_manage_checkouts,
        checkout.token,
        "Checkout",
        key="to_clear",
    )
    # then
    assert item_contains_proper_private_metadata(
        response["data"]["deletePrivateMetadata"]["item"],
        checkout.metadata_storage,
        checkout_id,
    )
    assert item_without_private_metadata(
        response["data"]["deletePrivateMetadata"]["item"],
        checkout.metadata_storage,
        checkout_id,
        key="to_clear",
    )