code: def test_lab2luv():
      cv_lab = cv.cvtColor(cv_bgr, cv.COLOR_BGR2RGB)
      cv_lab = caer.to_tensor(cv_lab, cspace="rgb")
      luv = caer.lab2luv(cv_lab)
  
      assert len(luv.shape) == 3
      assert isinstance(luv, caer.Tensor)
      assert luv.is_luv()
  
file_path: caer/tests/color/test_lab.py
imports: import caer
  import cv2
  import os
label_desc: Use image node_id 7 for calling a global function with example usage: test_lab2luv() without return types