text: class Flags(object):
      restart_after_phase = False
      request_restart_after_phase = False
      is_checkpoint = False
  
      def __init__(self,
                   request_restart_after_phase=False,
                   restart_after_phase=False,
                   is_checkpoint=False):
          self.request_restart_after_phase = request_restart_after_phase
          self.restart_after_phase = restart_after_phase
          self.is_checkpoint = is_checkpoint
  
      def serialize(self):
          """
          :return: Serialized data of phase flags
          """
          return {
              'restart_after_phase': self.restart_after_phase,
              'request_restart_after_phase': self.request_restart_after_phase,
              'is_checkpoint': self.is_checkpoint
          }
  