def rgb_color(red, green, blue, alpha = nil)
      attrs = {:red => red, :green => green, :blue => blue}
      attrs[:alpha] = alpha if alpha
      Color.new(attrs)
    end
def rgb_color(red, green, blue, alpha = nil)
      attrs = {:red => red, :green => green, :blue => blue}
      attrs[:alpha] = alpha if alpha
      Color.new(attrs)
    end
Construct a Sass Color from rgb values.

 @param red [::Number] The red component. Must be between 0 and 255 inclusive.
 @param green [::Number] The green component. Must be between 0 and 255 inclusive.
 @param blue [::Number] The blue component. Must be between 0 and 255 inclusive.
 @param alpha [::Number] The alpha channel. A number between 0 and 1.

 @return [Sass::Script::Value::Color] the color object