Apple Clang (clang-600.0.54 on x86_64-apple-darwin13.4.0) complains with: implicit instantiation of undefined template 'std::__1::hash<unsigned long long>'
Apple Clang (clang-600.0.54 on x86_64-apple-darwin13.4.0) complains with: implicit instantiation of undefined template 'std::__1::hash<unsigned long long>'