new_contents: from runner import ServerManager
  import time
  
  try:
      manager = ServerManager()
      manager.async_start_block_server(1234)
      manager.async_start_block_server(1235)
      manager.async_start_block_server(1236)
      manager.async_start_block_server(1237)
      while 1:
          time.sleep(0)
  except:
      manager.kill_all()
  
  
subject: Add start_cluster