# File lib/ruote/exp/flowexpression.rb, line 584
    def get_next_sub_wfid

      i = [
        $$, Time.now.to_f.to_s, self.hash.to_s, @h['fei'].inspect
      ].join('-').hash

      @@sub_wfid_counter = (@@sub_wfid_counter + 1) % 1000
      i = i * 1000 + (@@sub_wfid_counter)

      (i < 0 ? "1#{i * -1}" : "0#{i}").to_s
    end