code: def _rotate(img, angle):
          '''
          angle [DEG]
          '''
          s = img.shape
          if angle == 0:
              return img
          else:
              M = cv2.getRotationMatrix2D((s[1] // 2,
                                           s[0] // 2), angle, 1)
              return cv2.warpAffine(img, M, (s[1], s[0])f _rotate(img, angle):
          '''
          angle [DEG]
          '''
          s = img.shape
          if angle == 0:
              return img
          else:
              M = cv2.getRotationMatrix2D((s[1] // 2,
                                           s[0] // 2), angle, 1)
              return cv2.warpAffine(img, M, (s[1], s[0]))
docs: angle [DEG]