code: def test_fsdp_precision_default_scaler():
      from torch.distributed.fsdp.sharded_grad_scaler import (
          ShardedGradScaler,
      )
  
      precision = FSDPPrecision(precision="16-mixed")
      assert isinstance(precision.scaler, ShardedGradScaler)
  
file_path: pytorch-lightning/tests/tests_fabric/plugins/precision/test_fsdp.py
imports: from unittest.mock import Mock
  import pytest
  import torch
  from lightning.fabric.plugins import FSDPPrecision
  from lightning.fabric.plugins.precision.utils import _DtypeContextManager
  from tests_fabric.helpers.runif import RunIf
label_desc: Use image node_id 2 for calling a global function with example usage: test_fsdp_precision_default_scaler() without return types