local zones
    read -r -a zones <<< "${E2E_ZONES}"
    # tear them down in reverse order, finally tearing down the master too.
    for ((zone_num=${#zones[@]}-1; zone_num>0; zone_num--)); do
      KUBE_GCE_ZONE="${zones[zone_num]}" KUBE_USE_EXISTING_MASTER="true" "${KUBE_ROOT}/cluster/kube-down.sh"
    done
    KUBE_GCE_ZONE="${zones[0]}" KUBE_USE_EXISTING_MASTER="false" "${KUBE_ROOT}/cluster/kube-down.sh"

  struct AssertHelperData {
    AssertHelperData(TestPartResult::Type t,
                     const char* srcfile,
                     int line_num,
                     const char* msg)
        : type(t), file(srcfile), line(line_num), message(msg) { }

    TestPartResult::Type const type;
    const char* const file;
    int const line;
    std::string const message;

   private:

  struct AssertHelperData {
    AssertHelperData(TestPartResult::Type t,
                     const char* srcfile,
                     int line_num,
                     const char* msg)
        : type(t), file(srcfile), line(line_num), message(msg) { }

    TestPartResult::Type const type;
    const char* const file;
    int const line;
    std::string const message;

   private: