using duration = std::chrono::duration<rep, period>;
using time_point = std::chrono::time_point<SimulationClock, duration>;
static constexpr bool is_steady = true;
using duration = std::chrono::duration<rep, period>;
using time_point = std::chrono::time_point<SimulationClock, duration>;
static constexpr bool is_steady = true;