code: func (w *Waveform) Draw(values []float64) image.Image {
  	return w.generateImage(values)
  }
docs: // Draw creates a new image.Image from a slice of float64 values.
  //
  // Draw is typically used after a waveform has been computed one time, and a slice
  // of computed values was returned from the first computation.  Subsequent calls to
  // Draw may be used to customize a waveform using the same input values.