# File lib/ruote/fei.rb, line 107
    def self.to_storage_id(hfei)

      # TODO : for 2.1.13, remove the subid || sub_wfid trick

      if hfei.respond_to?(:to_storage_id)
        hfei.to_storage_id
      else
        "#{hfei['expid']}!#{hfei['subid'] || hfei['sub_wfid']}!#{hfei['wfid']}"
      end
    end