udls.cpp

#include <chrono>

using std::chrono_literals::operator ""h;

constexpr double operator "" _ping(unsigned long long ping)
{
    return double(ping);
}

constexpr double operator "" pong(unsigned long long pong)
{
    return double(pong);
}

int main(void) {
  auto hour = 3h;
  double x = 12_ping;
  double y = 13pong;
  return 0;
}