code: def test_empty_list(self):
      classifier = DocumentLanguageClassifier()
      result = classifier.run(documents=[])
      assert result == {"documents": []}
  
file_path: haystack/test/components/classifiers/test_document_language_classifier.py
imports: import logging
  import pytest
  from haystack import Document
  from haystack.components.classifiers import DocumentLanguageClassifier
label_desc: Use image node_id 4 for calling the TestDocumentLanguageClassifier obj's underlying member method code with example usage: obj.test_empty_list() without return types