# File lib/sass/script/functions.rb, line 482
    def hsla(hue, saturation, lightness, alpha)
      assert_type hue, :Number, :hue
      assert_type saturation, :Number, :saturation
      assert_type lightness, :Number, :lightness
      assert_type alpha, :Number, :alpha

      Sass::Util.check_range('Alpha channel', 0..1, alpha)

      h = hue.value
      s = Sass::Util.check_range('Saturation', 0..100, saturation, '%')
      l = Sass::Util.check_range('Lightness', 0..100, lightness, '%')

      Color.new(:hue => h, :saturation => s, :lightness => l, :alpha => alpha.value)
    end