code: def test_forward_context(precision, expected_dtype):
      precision = HalfPrecision(precision=precision)
      assert torch.get_default_dtype() == torch.float32
      with precision.forward_context():
          assert torch.get_default_dtype() == expected_dtype
      assert torch.get_default_dtype() == torch.float32
  
imports: import pytest
  import torch
  from lightning.pytorch.plugins import HalfPrecision
label_desc: Use image node_id 3 for calling a global function with example usage: test_forward_context(precision, expected_dtype) without return types