code: def square_worker(a):
      return a**2
  
imports: import fiber
  import multiprocessing
  import time
  import pytest
  import docker
  import fiber.config
  from fiber.docker_backend import Backend
  from fiber.util import find_ip_by_net_interface
  import psutil
  import ipaddress
  import socket
label_desc: Use image node_id 2 for calling a global function with example usage: square_worker(a) and returns: unknown