# File lib/facet/lisp-format.rb, line 787
        def execute(state)
          if @params.size > 0
            # XXX: may be ugly to modify these
            n = @params.shift.value
            Factory.build(@params, @modifiers, nil, @pos, n).execute(state)
          else
            arg = state.next_arg
            if arg.respond_to? :to_int
              conversion = :cardinal
              conversion = :ordinal if colon_mod?
              conversion = :roman if at_mod?
              conversion = :old_roman if colon_mod? and at_mod?
              state.output self.send(conversion, arg.to_int)
            else
              arg_error 'argument is not an integer'
            end
          end
        end