code: def union_box(box1, box2):
      """
      Params:
          box1: [x1, y1, x2, y2]
          box2: [x1, y1, x2, y2]
      """
      x1 = min(box1[0], box2[0])
      y1 = min(box1[1], box2[1])
      x2 = max(box1[2], box2[2])
      y2 = max(box1[3], box2[3])
  
      return [x1, y1, x2, y2]
  
imports: from typing import List, Union, Any, Tuple, Optional
  import requests
  import torch
  from langchain.docstore.document import Document
  from langchain.document_loaders import ImageCaptionLoader
  import numpy
  from utils import get_device, clear_torch_cache, NullContext
  from doctr.utils.common_types import AbstractFile
label_desc: Use image node_id 3 for calling a global function with example usage: union_box(box1, box2) and returns: list