# File lib/facet/lisp-format.rb, line 673
        def execute(state)
          mincol = param(0, state, 0)
          padchar = param(1, state, ?\s).chr
          commachar = param(2, state, ?,).chr
          interval = param(3, state, 3)
          arg = state.next_arg
          if arg.respond_to? :to_int
            num = arg.to_int
            str = num.to_s(@radix)
            if colon_mod?
              str.gsub!(/(\d)(?=(\d{#{interval}})+(?!\d))/, "\\1#{commachar}")
            end
            str = '+' + str if at_mod? and num >= 0
#             puts(str.rjust(mincol, '-'))
            state.output str.rjust(mincol, padchar)
          else
            arg_error 'argument is not an integer'
          end
        end