function displaySongWaveform(element, svg, song) {
    /*
      Ensure it's the active song being displayed.
    */
    if (_config2.default.active_index == song) {
      var waveformPath = element.querySelector("svg g path");

      waveformPath.setAttribute("d", svg);
    }
  }
Displays a song wave form.

@param {Node} element - Element to display the waveform in.
@param {SVG} svg - The waveform path.
@param {Integer} song - The index of the song we are displaying the
waveform for.