# File lib/ruote/fei.rb, line 99
    def self.to_storage_id (hfei)

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