dialogs = []
limit = 100
offset_date = 0
while True:
  try:
    d = app.send(functions.messages.GetDialogs(offset_date=offset_date, offset_id=0, limit=limit, offset_peer=types.InputPeerEmpty()))
  except FloodWait as e:
    time.sleep(e.x)
    logging.error('Код ошибки 420.')
    print("\nПодождите {} секунд(ы)".format(e.x), end='\r', flush=True)
    continue

  if not d.dialogs:
    break

  dialogs += d.dialogs
  offset_date = d.messages[-1].date