code: def test_remove_empty_lines(self):
      cleaner = DocumentCleaner(remove_extra_whitespaces=False)
      result = cleaner.run(
          documents=[
              Document(
                  content="This is a text with some words. "
                  ""
                  "There is a second sentence. "
                  ""
                  "And there is a third sentence."
              )
          ]
      )
      assert len(result["documents"]) == 1
      assert (
          result["documents"][0].content
          == "This is a text with some words. There is a second sentence. And there is a third sentence."
      )
  
file_path: haystack/test/components/preprocessors/test_document_cleaner.py
imports: import logging
  import pytest
  from haystack import Document
  from haystack.components.preprocessors import DocumentCleaner
label_desc: Use image node_id 5 for calling the TestDocumentCleaner obj's underlying member method code with example usage: obj.test_remove_empty_lines() without return types