text: import time
  
  
  class BaseCommand(object):
      __command_name__ = ''
  
      def __init__(self, database_connection, command_options, filters=None):
          self._filters = filters
          self._database_connection = database_connection
          self._refresh = command_options['refresh']
  
      def start(self):
          start_time = time.time()
  
          while True:
              yield self._do()
              time.sleep(self._refresh - ((time.time() - start_time) % 1.0))
  
      def _do(self):
          raise NotImplementedError()
  