code: def test_patch_fp64(self):
      from bigdl.nano.pytorch.patching import patch_dtype
  
      patch_dtype(from_dtype="fp64", to_dtype="fp32")
  
      # default dtype
      assert torch.rand(1, 2).dtype == torch.float32
  
      # patch fp64
      assert (
          torch.rand(1, 2, dtype=torch.float64).dtype == torch.float32
      )
  
      # double
      tensor = torch.rand(1, 2).double()
      assert tensor.dtype == torch.float32
  
file_path: BigDL/python/nano/test/pytorch/tests/test_dispatcher.py
imports: from unittest import TestCase
  import tempfile
  import os
  import pytest
  import torch
  from bigdl.nano.utils.common import invalidOperationError
  from bigdl.nano.utils.pytorch import TORCH_VERSION_LESS_1_10
label_desc: Use image node_id 4 for calling the TestDispatcherPytorch obj's underlying member method code with example usage: obj.test_patch_fp64() without return types