code: def test_window_union():
      assert windows.union(
          windows.Window(0, 3, 3, 6), windows.Window(2, 1, 2, 4)
      ) == windows.Window(0, 1, 4, 8)
  
imports: import numpy
  import pytest
  import rasterio
  from rasterio.errors import WindowError
  from rasterio import windows
label_desc: Use image node_id 16 for calling a global function with example usage: test_window_union() without return types