static Timer* set(double date, xbt::Task<void()>&& callback);
static double next() { return kernel_timers().empty() ? -1.0 : kernel_timers().top().first; }
static Timer* set(double date, xbt::Task<void()>&& callback);
static double next() { return kernel_timers().empty() ? -1.0 : kernel_timers().top().first; }