input: def clean_html_tags(str):
      """ Clean a string of HTML tags
      >>> clean_html_tags("<p>This is a <b>test</b> string</p>")
      'This is a test string'
      >>> clean_html_tags("<div><h1>Title</h1><p>Content</p></div>")
      'TitleContent'
      """
      import re
      clean_str = re.sub("<.*?>", "", str)
      return clean_str
output:     import re
      clean_str = re.sub("<.*?>", "", str)
      return clean_str