code: def square_worker(a):
      return a**2
  
imports: import pytest
  import time
  import math
  import select
  import fiber
  import docker
  import requests
  from fiber import Process
  from fiber.docker_backend import Backend
  import fiber.config
label_desc: Use image node_id 4 for calling a global function with example usage: square_worker(a) and returns: unknown