code: def flush(self):
      with self.lock:
          if not self.data:
              return
  
      self.app_tracker.has_data(self)
  
imports: import threading
  import time
  from typing import Dict
  from typing import Union
  import numpy
  from ..app import AppTracker, Packet, AppTrackDataSource
  from ..app.url import AppUrlResponseHandler
label_desc: Use image node_id 5 for calling the Writer obj's underlying member method code with example usage: obj.flush() without return types