 any drawn waves now because
      // we're not going to get another requestAnimationFrame any more.
      var ctx = elem.getContext('2d');
      ctx.clearRect(0, 0, elem.width, elem.height);
    }

    // Draw the label at the very last point so it is on top of everything.
    drawLabel(elem, scope.label, scope.labelFontSize, fgColor, elem.style.textAlign);

    for (var i = 0; i < deleteTheseWaves.length; ++i) {
      var wave = deleteTheseWaves[i];
      removeWaveFromScope(scope, wave);
    }
  };

  //