code: def test_pagejoin(self):
      image = pyvips.Image.new_from_file(JPEG_FILE)
      many_page = image.pagejoin([image, image])
      assert many_page.get_page_height() == image.height
      assert many_page.height / many_page.get_page_height() == 3
  
file_path: pyvips/tests/test_image.py
imports: import pyvips
  import pytest
  from helpers import JPEG_FILE
label_desc: Use image node_id 1 for calling the TestImage obj's underlying member method code with example usage: obj.test_pagejoin() without return types