public void UnregisterSpeedChangeHandler(SpeedChangeHandler handler)
 {
     speedChangeHandler -= handler;
 }
 public void UnregisterSpeedChangeHandler(SpeedChangeHandler handler)
 {
     speedChangeHandler -= handler;
 }
 public void RegisterSpeedChangeHandler(SpeedChangeHandler handler)
 {
     speedChangeHandler += handler;
 }
 public void RegisterSpeedChangeHandler(SpeedChangeHandler handler)
 {
     speedChangeHandler += handler;
 }