# File lib/compass/sass_extensions/functions/gradient_support.rb, line 520
    def assert_type(value, type, name = nil)
      return if value.is_a?(Sass::Script.const_get(type))
      err = "#{value.inspect} is not a #{type.to_s.downcase}"
      err = "$#{name}: " + err if name
      raise ArgumentError.new(err)
    end