@Override
	public Boolean call() 
			throws SongFeatureException {
		
		Boolean resH, resL;
		
		if(this.hlEvaluation)
			resH= false;
		else
			resH= true;
		
		if(this.llEvaluation)
			resL= false;
		else
			resL= true;
			
		if(this.hlEvaluation)
			resH= HighLevelSongFeature.start(this);
		
		if(this.llEvaluation)
			resL= LowLevelSongFeature.start(this, this.song);
				
		return (resH && resL);
	}