input: Write a python function to clean text by removing punctuation, converting to lowercase, and stripping leading/trailing whitespace.
  assert clean_text('This is a sample sentence.') == 'this is a sample sentence'
  assert clean_text('  Hello, World!  ') == 'hello world'
  assert clean_text('Python3.8 is great!!!') == 'python38 is great'
output: def clean_text(text):
      import string
      text = text.lower()
      text = text.translate(str.maketrans('', '', string.punctuation))
      text = text.strip()
      return text