procedure decol(s, i)
   local parts, j, form

   parts := list(i, "|")

   s ? {
      repeat {
         every j := 1 to i do {
            (parts[j] ||:= move(1)) | break break
            }
         }
      }

   form := ""

   every form ||:= !parts

   return "{" || form[2:0] || "}"

end