Saturate a hex color.

def saturate_color(color, amount):
    """Saturate a hex color."""
    r, g, b = hex_to_rgb(color)
    r, g, b = [x/255.0 for x in (r, g, b)]
    h, l, s = colorsys.rgb_to_hls(r, g, b)
    s = amount
    r, g, b = colorsys.hls_to_rgb(h, l, s)
    r, g, b = [x*255.0 for x in (r, g, b)]

    return rgb_to_hex((int(r), int(g), int(b)))