# File lib/ruote/svc/tracker.rb, line 110
    def remove(tracker_ids, wfid)

      return if tracker_ids.empty?

      doc ||= @context.storage.get_trackers(wfid)

      return if (doc['trackers'].keys & tracker_ids).empty?

      doc['wfid'] = wfid
        # a little helper for some some storage implementations like ruote-swf
        # they need to know what workflow execution is targetted.

      tracker_ids.each { |ti| doc['trackers'].delete(ti) }
      r = @context.storage.put(doc)

      remove(tracker_ids, wfid) if r
        # the put failed, have to redo the work
    end