# File lib/facet/lisp-format.rb, line 182
      def args_move(n = 1, relative = true)
        @arg_pos = relative ? @arg_pos + n : n
        raise IndexError.new,
          'too few arguments' if @arg_pos > @args.size
        raise IndexError.new,
          'cannot move past first argument' if @arg_pos < 0
      end