input: Write a function to clean text data by converting it to lowercase using lambda function.
  assert clean_text('Hello World') == 'hello world'
  assert clean_text('Spam Messages ARE Annoying') == 'spam messages are annoying'
  assert clean_text('123 ABC def!') == '123 abc def!'
output: def clean_text(text):
      return (lambda x: x.lower())(text)