code: def test_check_llm_quantization_backend_incompatibility():
      config = yaml.safe_load(
          """
  model_type: llm
  base_model: facebook/opt-350m
  quantization:
    bits: 4
  input_features:
    - name: sample
      type: text
  output_features:
    - name: label
      type: text
  backend:
    type: ray
  """
      )
  
      with pytest.raises(ConfigValidationError):
          ModelConfig.from_dict(config)
  
      config["backend"]["type"] = "local"
      ModelConfig.from_dict(config)
  
      del config["backend"]
      ModelConfig.from_dict(config)
  
      del config["quantization"]
      config["backend"] = {"type": "ray"}
      ModelConfig.from_dict(config)
  
imports: import contextlib
  from typing import Any, Dict, List, Optional
  import pytest
  import yaml
  from ludwig.constants import COMBINER, TYPE
  from ludwig.error import ConfigValidationError
  from ludwig.schema.model_types.base import ModelConfig
  from tests.integration_tests.utils import binary_feature, text_feature
label_desc: Use image node_id 16 for calling a global function with example usage: test_check_llm_quantization_backend_incompatibility() without return types