code: def test_attn_mixer(self):
      attn_mixer = AttnMixer(embed_dims=self.img.shape[-1])
      self.assertEqual(
          attn_mixer(self.img).shape, torch.Size([1, 8 * 25, 768])
      )
  
imports: from unittest import TestCase
  import torch
  from mmocr.models.textrecog.encoders.svtr_encoder import AttnMixer, ConvMixer, MerigingBlock, MixingBlock, OverlapPatchEmbed, SVTREncoder
label_desc: Use image node_id 2 for calling the TestAttnMixer obj's underlying member method code with example usage: obj.test_attn_mixer() without return types