Function GetKey

tensorflow/core/lib/gtl/subtle/map_traits.h:36–38

template <class V>
auto GetKey(V&& v, Rank0) -> decltype((std::forward<V>(v).first)) {
  return std::forward<V>(v).first;
}
template <class V>
auto GetKey(V&& v, Rank1) -> decltype(std::forward<V>(v).key()) {
  return std::forward<V>(v).key();