code: public final static Sample append(List<Sample> samples) {
          if (samples.size() == 0) {
              return buildSample(0, new double[0]);
          }
  
          int sampleCount = 0;
  
          // append voices to each other
          double[] first = samples.get(0).getInterleavedSamples();
          sampleCount += samples.get(0).getSampleCount();
  
          double[][] samples_ary = new double[samples.size() - 1][];
          for (int i = 0; i < samples_ary.length; i++) {
              samples_ary[i] = samples.get(i + 1).getInterleavedSamples();
              sampleCount += samples.get(i + 1).getSampleCount();
          }
  
          double[] appended = concatAll(first, samples_ary);
  
          return buildSample(sampleCount, appended);
      }
docs: <p>append.</p>
  
  @param samples a {@link java.util.List} object.
  @return a {@link ameba.captcha.audio.Sample} object.