code: def start_crossbar(self):
      if self.crossbar_process is not None:
          self.stop_crossbar()
  
      crossbar_command = f"crossbar start --config crossbar.json"
  
      self.crossbar_process = subprocess.Popen(
          shlex.split(crossbar_command)
      )
  
      signal.signal(signal.SIGINT, self._handle_signal_crossbar)
      signal.signal(signal.SIGTERM, self._handle_signal_crossbar)
  
      atexit.register(self._handle_signal_crossbar, 15, None, False)
  
imports: import warnings
  import offshoot
  import subprocess
  import signal
  import shlex
  import time
  import os, os.path
  import atexit
  from serpent.game_agent import GameAgent
  from serpent.game_launchers import *
  from serpent.window_controller import WindowController
  from serpent.input_controller import InputController, InputControllers
  from serpent.frame_grabber import FrameGrabber
  from serpent.game_frame_limiter import GameFrameLimiter
  from serpent.sprite import Sprite
  from serpent.utilities import clear_terminal, is_windows, SerpentError
  import skimage.io
  import skimage.color
  import numpy
  from redis import StrictRedis
  from serpent.config import config
label_desc: Use image node_id 17 for calling the Game obj's underlying member method code with example usage: obj.start_crossbar() without return types