old_contents: import logging
  from flexget.plugin import get_plugins_by_group, register_plugin
  
  log = logging.getLogger('est_released')
  
  
  class EstimateRelease(object):
  
      """
      Front-end for estimator plugins that estimate release times
      for various things (series, movies).
      """
  
      def estimate(self, entry):
          """
          Estimate release schedule for Entry
  
          :param entry:
          :return: estimated date of released for the entry, None if it can't figure it out
          """
  
          log.info(entry['title'])
          estimators = get_plugins_by_group('estimate_release')
          for estimator in estimators:
              return estimator.instance.estimate(entry)
  
  register_plugin(EstimateRelease, 'estimate_release', api_ver=2)
  
new_contents: import logging
  from flexget.plugin import get_plugins_by_group, register_plugin
  
  log = logging.getLogger('est_released')
  
  
  class EstimateRelease(object):
  
      """
      Front-end for estimator plugins that estimate release times
      for various things (series, movies).
      """
  
      def estimate(self, entry):
          """
          Estimate release schedule for Entry
  
          :param entry:
          :return: estimated date of released for the entry, None if it can't figure it out
          """
  
          log.info(entry['title'])
          estimators = get_plugins_by_group('estimate_release')
          for estimator in estimators:
              estimate = estimator.instance.estimate(entry)
              # return first successful estimation
              if estimate is not None:
                  return estimate
  
  register_plugin(EstimateRelease, 'estimate_release', api_ver=2)
  
subject: Fix estimator loop, consider rest plugins as well.