input: Write a python function to search for a keyword in a document, ensuring the search is case insensitive, and print the lines where the keyword is found.
  assert search_document("test_doc.txt", "Python") is None  # Assuming "Python" appears in some lines
  assert search_document("test_doc.txt", "java") is None  # Assuming "java" appears in some lines
  assert search_document("test_doc.txt", "notfound") is None  # Assuming "notfound" does not appear in the document
output: def search_document(file_path, keyword):
      keyword = keyword.lower()
      try:
          with open(file_path, 'r') as file:
              lines = file.readlines()
              for line in lines:
                  if keyword in line.lower():
                      print(line.strip())
      except FileNotFoundError:
          print(f"File {file_path} not found.")