public TraceStep startStep(String call, IStatsProducer producer, String methodName){
		TraceStep last = current;
		current = new TraceStep(call, producer, methodName);
		//it actually happened in production, we are still investigating why, but this fix should at least prevent the NPE for now.
		if (last!=null)
			last.addChild(current);
		return current;
	}
public TraceStep startStep ( String call , IStatsProducer producer , String methodName ) { TraceStep last = current ; current = new TraceStep ( call , producer , methodName ) ; if ( last != null ) last . addChild ( current ) ; return current ; }
Creates a new sub step in current call.