# File lib/cairo/color.rb, line 168
      def initialize(c, m, y, k, a=1.0)
        super(a)
        assert_in_range(c, "cyan")
        assert_in_range(m, "magenta")
        assert_in_range(y, "yellow")
        assert_in_range(k, "key plate")
        @cyan = c
        @magenta = m
        @yellow = y
        @key_plate = k
      end