Custom Sass function for Array#include?

include.rb

module Sass::Script::Functions
  # Wrapper around Ruby's Array#include? method.
  # https://gist.github.com/4088394
  #
  # value - Value to check for in the list.
  # list  - List to look through.
  #
  # Examples
  #   
  #   $list: a b c;
  #   @debug contains(b, $list);
  #   # => true
  #
  # Returns True if the value is found in the list, false if it isn't.
  def contains(value, list)
    assert_type list, :List
    
    Sass::Script::Bool.new(list.value.include?(value))
  end
  declare :contains, [:value, :list]
end