code: function setBrightness(brightness) {
    validateBrightness(brightness, false);
  
    for (var i = 0; i < NUM_PIXELS; i++) {
      pixels[i][3] = toBrightnessValue(brightness);
    }
  }
docs: Sets the brightness of all pixels to <code>brightness</code>.
  
  @param {number} brightness - the brightness to be set (between 0 and 1 - inclusive)
  @return {void}
  @throws {RangeError} If <code>brightness</code> is less than 0 or greater than 1.
  @throws {TypeError} If <code>brightness</code> is <code>null</code> or not a number.
  @public