public AcousticInstrument(MusicInstrument instrument)
     : base(instrument)
 {
 }
 public bool SetInstrument(MusicInstrument instrument)
 {
     _instrument = instrument;
     return(true);
 }
 public ElectroInstrument(MusicInstrument instrument) : base(instrument)
 {
 }
 public Decorator(MusicInstrument instrument)
 {
     _instrument = instrument;
 }