code: def test_detect_language(self):
      classifier = DocumentLanguageClassifier()
      detected_language = classifier.detect_language(
          Document(content="This is an english sentence.")
      )
      assert detected_language == "en"
  
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 5 for calling the TestDocumentLanguageClassifier obj's underlying member method code with example usage: obj.test_detect_language() without return types