def string_literal(string)
      Literal.new(Sass::Script::Value::String.new(string, :string))
    end
def string_literal(string)
      Literal.new(Sass::Script::Value::String.new(string, :string))
    end
Returns a string literal with the given contents.

 @param string [String]
 @return string [Sass::Script::Tree::Literal]