code: def test_amp_precision_optimizer_step_without_scaler():
      precision = MixedPrecision(precision="bf16-mixed", device="cuda")
      assert precision.scaler is None
      optimizer = Mock()
  
      precision.optimizer_step(optimizer, keyword="arg")
      optimizer.step.assert_called_once_with(keyword="arg")
  
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 6 for calling a global function with example usage: test_amp_precision_optimizer_step_without_scaler() without return types