input: Write a python function to normalize a given string by converting it to lowercase, stripping whitespace, and removing punctuation.
  assert normalize_string("  Hello, World!  ") == "hello world"
  assert normalize_string("Python's Awesome...") == "pythons awesome"
  assert normalize_string(" Normalize THIS!! ") == "normalize this"
output: import string
  
  def normalize_string(s):
      s = s.lower().strip()
      s = s.translate(str.maketrans('', '', string.punctuation))
      return s