code: def test_detect_language(self):
      classifier = TextLanguageRouter()
      detected_language = classifier.detect_language(
          "This is an english sentence."
      )
      assert detected_language == "en"
  
file_path: haystack/test/components/routers/test_text_language_router.py
imports: import logging
  import pytest
  from haystack import Document
  from haystack.components.routers import TextLanguageRouter
label_desc: Use image node_id 4 for calling the TestTextLanguageRouter obj's underlying member method code with example usage: obj.test_detect_language() without return types