# File lib/sass/script/parser.rb, line 216
      def parse_string
        unless (peek = @lexer.peek) &&
            (peek.type == :string ||
            (peek.type == :funcall && peek.value.downcase == 'url'))
          lexer.expected!("string")
        end

        expr = assert_expr :funcall
        check_for_interpolation expr
        expr.options = @options
        @lexer.unpeek!
        expr
      rescue Sass::SyntaxError => e
        e.modify_backtrace :line => @lexer.line, :filename => @options[:filename]
        raise e
      end