old_contents: #!/usr/bin/env python
  from flask import Flask, render_template, Response
  
  # emulated camera
  from camera import Camera
  
  # Raspberry Pi camera module (requires picamera package)
  # from camera_pi import Camera
  
  app = Flask(__name__)
  
  
  @app.route('/')
  def index():
      """Video streaming home page."""
      return render_template('index.html')
  
  
  def gen(camera):
      """Video streaming generator function."""
      while True:
          frame = camera.get_frame()
          yield (b'--frame\r\n'
                 b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n')
  
  
  @app.route('/video_feed')
  def video_feed():
      """Video streaming route. Put this in the src attribute of an img tag."""
      return Response(gen(Camera()),
                      mimetype='multipart/x-mixed-replace; boundary=frame')
  
  
  if __name__ == '__main__':
      app.run(host='0.0.0.0', debug=True)
  
new_contents: #!/usr/bin/env python
  from flask import Flask, render_template, Response
  
  # emulated camera
  from camera import Camera
  
  # Raspberry Pi camera module (requires picamera package)
  # from camera_pi import Camera
  
  app = Flask(__name__)
  
  
  @app.route('/')
  def index():
      """Video streaming home page."""
      return render_template('index.html')
  
  
  def gen(camera):
      """Video streaming generator function."""
      while True:
          frame = camera.get_frame()
          yield (b'--frame\r\n'
                 b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n')
  
  
  @app.route('/video_feed')
  def video_feed():
      """Video streaming route. Put this in the src attribute of an img tag."""
      return Response(gen(Camera()),
                      mimetype='multipart/x-mixed-replace; boundary=frame')
  
  
  if __name__ == '__main__':
      app.run(host='0.0.0.0', debug=True, threaded=True)
  
subject: Update app.py