code: boolean decorateAtLast(byte[] decorator) {
          if (numTranscoders == 0) return decorateAt(decorator, 0);
          Transcoder transcoder = elements[numTranscoders - 1].transcoding.transcoder;
  
          if (!decorator(transcoder.source, transcoder.destination) && transcoder.compatibility.isEncoder()) {
              return decorateAt(decorator, numTranscoders - 1);
          }
  
          return decorateAt(decorator, numTranscoders);
      }
docs: /* rb_econv_decorate_at_last