code: def _annotate(self, frame: np.ndarray, results: NamedTuple, idx: int):
      for detection in results.detections:
          mp_drawing.draw_detection(frame, detection)
      path = os.path.join(
          tempfile.gettempdir(),
          self.id().split(".")[-1] + "_frame_{}.png".format(idx),
      )
      cv2.imwrite(path, frame)
  
file_path: mediapipe/mediapipe/python/solutions/face_detection_test.py
imports: import os
  import tempfile
  from typing import NamedTuple
  from absl.testing import absltest
  from absl.testing import parameterized
  import cv2
  import numpy
  import numpy.testing
  from mediapipe.python.solutions import drawing_utils
  from mediapipe.python.solutions import face_detection
label_desc: Use image node_id 1 for calling the FaceDetectionTest obj's underlying member method code with example usage: obj._annotate(frame, results, idx) without return types