code: def test_submeshes(self):
      N = 2
      V = 5
      F = 5
      tex = TexturesAtlas(
          atlas=torch.arange(
              N * F * 4 * 4 * 3, dtype=torch.float32
          ).reshape(N, F, 4, 4, 3)
      )
  
      verts = torch.rand(size=(N, V, 3))
      faces = torch.randint(size=(N, F, 3), high=V)
      mesh = Meshes(verts=verts, faces=faces, textures=tex)
  
      sub_faces = [
          [torch.tensor([0, 2]), torch.tensor([1, 2])],
          [],
      ]
      subtex = mesh.submeshes(sub_faces).textures
      subtex_faces = subtex.atlas_list()
  
      self.assertEqual(len(subtex_faces), 2)
      self.assertClose(
          subtex_faces[0].flatten().msort(),
          torch.cat(
              (
                  torch.arange(4 * 4 * 3, dtype=torch.float32),
                  torch.arange(96, 96 + 4 * 4 * 3, dtype=torch.float32),
              ),
              0,
          ),
      )
  
imports: import unittest
  import torch
  import torch.nn.functional
  from pytorch3d.renderer.mesh.rasterizer import Fragments
  from pytorch3d.renderer.mesh.textures import _list_to_padded_wrapper, TexturesAtlas, TexturesUV, TexturesVertex
  from pytorch3d.renderer.mesh.utils import pack_rectangles, pack_unique_rectangles, Rectangle
  from pytorch3d.structures import list_to_packed, Meshes, packed_to_list
  from .common_testing import TestCaseMixin
  from .test_meshes import init_mesh
label_desc: Use image node_id 11 for calling the TestTexturesAtlas obj's underlying member method code with example usage: obj.test_submeshes() without return types