code: def prev_id(current_id, worker_num):
      if current_id == 1:
          return worker_num
      else:
          return current_id - 1
  
file_path: face_recognition/examples/facerec_from_webcam_multiprocessing.py
imports: import face_recognition
  import cv2
  from multiprocessing import Process, Manager, cpu_count, set_start_method
  import time
  import numpy
  import threading
  import platform
label_desc: Use image node_id 2 for calling a global function with example usage: prev_id(current_id, worker_num) and returns: worker_num, unknown