code: def dirs(self, before=time.time(), exited=True):
          
          timestamp = iso(before)
          root = os.path.join(self.root, "start-time")
          os.chdir(root)
          by_t = (d for d in glob.iglob("????-??-??T*.*Z") if d < timestamp)
          if exited is None:
              def predicate(directory):
                  return True
          else:
              def predicate(directory):
                  exit = os.path.join(directory, "exit")
                  return os.path.exists(exit) is exited
          return (os.path.join(root, d) for d in by_t if predicate(d))
docs: Provider a generator of container state directories.
  
          If exited is None, all are returned. If it is False, unexited
          containers are returned. If it is True, only exited containers are
          returned.