instant/native.rs
pub type Instant = std::time::Instant;
pub type SystemTime = std::time::SystemTime;
/// The current time, expressed in milliseconds since the Unix Epoch.
pub fn now() -> f64 {
std::time::SystemTime::now().duration_since(std::time::SystemTime::UNIX_EPOCH)
.expect("System clock was before 1970.")
.as_secs_f64() * 1000.0
}