code: def test_init(self):
      with self.assertRaises(AssertionError):
          FPN_UNet(self.in_channels + [128], self.out_channels)
      with self.assertRaises(AssertionError):
          FPN_UNet(self.in_channels, [2, 4])
  
imports: import unittest
  import torch
  from mmocr.models.textdet.necks import FPN_UNet
label_desc: Use image node_id 2 for calling the TestFPNUnet obj's underlying member method code with example usage: obj.test_init() without return types