docstr: Test init multi instance RoI head.
code: def test_init(self):
      """Test init multi instance RoI head."""
      roi_head_cfg = _fake_roi_head()
      roi_head = MODELS.build(roi_head_cfg)
      self.assertTrue(roi_head.with_bbox)
  
file_path: mmdetection/tests/test_models/test_roi_heads/test_multi_instance_roi_head.py
imports: import unittest
  from unittest import TestCase
  import torch
  from mmengine.config import Config
  from mmdet.registry import MODELS
  from mmdet.testing import demo_mm_inputs, demo_mm_proposals
  from mmdet.utils import register_all_modules
label_desc: Use image node_id 1 for calling the TestMultiInstanceRoIHead obj's underlying member method code with example usage: obj.test_init() without return types