code: function setPixel(index, red, green, blue, brightness) {
    validateIndex(index);
    validateRGB(red, green, blue);
    validateBrightness(brightness, true);
  
    setPixelInternal(index, red, green, blue, brightness);
  }
docs: Sets the specified RGB values, and optionally <code>brightness</code>, of the pixel at the <code>index</code>
  provided.
  
  If you don't supply a <code>brightness</code> value, the last value set will be kept.
  
  @param {number} index - the horizontal position of the pixel (between 0 and 7 - inclusive)
  @param {number} red - the amount of red to be set (between 0 and 255 - inclusive)
  @param {number} green - the amount of green to be set (between 0 and 255 - inclusive)
  @param {number} blue - the amount of blue to be set (between 0 and 255 - inclusive)
  @param {number} [brightness] - the brightness to be set (between 0 and 1 - inclusive)
  @return {void}
  @throws {RangeError} If <code>index</code> is less than 0 or greather than 7, <code>brightness</code> is less than 0
  or greater than 1, or any color is less than 0 or greater than 255.
  @throws {TypeError} If <code>index</code> or any color are <code>null</code> or not a number, or
  <code>brightness</code> is not a number.
  @public