docstr: Test init rpn head.
code: def test_init(self):
      """Test init rpn head."""
      rpn_head = RPNHead(num_classes=1, in_channels=1)
      self.assertTrue(rpn_head.rpn_conv)
      self.assertTrue(rpn_head.rpn_cls)
      self.assertTrue(rpn_head.rpn_reg)
  
      # rpn_head.num_convs > 1
      rpn_head = RPNHead(num_classes=1, in_channels=1, num_convs=2)
      self.assertTrue(rpn_head.rpn_conv)
      self.assertTrue(rpn_head.rpn_cls)
      self.assertTrue(rpn_head.rpn_reg)
  
file_path: mmdetection/tests/test_models/test_dense_heads/test_rpn_head.py
imports: from unittest import TestCase
  import pytest
  import torch
  from mmengine import Config
  from mmengine.structures import InstanceData
  from mmdet import *
  from mmdet.models.dense_heads import RPNHead
label_desc: Use image node_id 1 for calling the TestRPNHead obj's underlying member method code with example usage: obj.test_init() without return types