code: def _rot90(self, img, num):
      num = num % 4  # note: -1 % 4 == 3
      for _ in range(num):
          img = img.transpose(0, 1).flip(0)
      return img
  
file_path: detectron2/tests/layers/test_roi_align_rotated.py
imports: import logging
  import unittest
  import cv2
  import torch
  from torch.autograd import Variable, gradcheck
  from detectron2.layers.roi_align import ROIAlign
  from detectron2.layers.roi_align_rotated import ROIAlignRotated
label_desc: Use image node_id 2 for calling the ROIAlignRotatedTest obj's underlying member method code with example usage: obj._rot90(img, num) and returns: img