code: func (wav *Reader) ReadRawSample() ([]byte, error) {
  	if wav.samplesRead > wav.numSamples {
  		return nil, io.EOF
  	}
  
  	buf := make([]byte, wav.bytesPerSample)
  	n, err := wav.input.Read(buf)
  	if err != nil {
  		return nil, err
  	}
  
  	if n != int(wav.bytesPerSample) {
  		return nil, fmt.Errorf("Read %d bytes, should have read %d", n, wav.bytesPerSample)
  	}
  
  	wav.samplesRead++
  
  	return buf, nil
  }
docs: // ReadRawSample returns the raw []byte slice