code: def test_amp_precision_default_scaler():
      precision = MixedPrecision(precision="16-mixed", device=Mock())
      assert isinstance(precision.scaler, torch.cuda.amp.GradScaler)
  
file_path: pytorch-lightning/tests/tests_fabric/plugins/precision/test_amp.py
imports: import re
  from unittest.mock import Mock
  import pytest
  import torch
  from lightning.fabric.plugins.precision.amp import MixedPrecision
label_desc: Use image node_id 1 for calling a global function with example usage: test_amp_precision_default_scaler() without return types