code: func (c Color) Hex() int32 {
  	if c&ColorIsRGB != 0 {
  		return (int32(c) & 0xffffff)
  	}
  	if v, ok := ColorValues[c]; ok {
  		return v
  	}
  	return -1
  }
docs: // Hex returns the color's hexadecimal RGB 24-bit value with each component
  // consisting of a single byte, ala R << 16 | G << 8 | B.  If the color
  // is unknown or unset, -1 is returned.