input: def clean_html_tags(str: str) -> str:
      """ Remove all html tags from the input string
      >>> clean_html_tags("<p>This is a <b>test</b> string</p>")
      'This is a test string'
      >>> clean_html_tags("No tags here, just plain text")
      'No tags here, just plain text'
      """
      import re
      clean_str = re.sub("<.*?>", "", str)
      return clean_str
output:     import re
      clean_str = re.sub("<.*?>", "", str)
      return clean_str