input: 
  import re
  
  def clean_html_tags(str: str) -> str:
      """ Cleans a string of HTML tags by removing all tags.
      >>> clean_html_tags("<p>This is a <b>test</b> string</p>")
      'This is a test string'
      >>> clean_html_tags("No tags here")
      'No tags here'
      >>> clean_html_tags("")
      ''
      >>> clean_html_tags("<div><p>Inner text</p></div>")
      'Inner text'
      """
      return re.sub(r"<.*?>", "", str)
  
output:     return re.sub(r"<.*?>", "", str)