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>Another <a href='#'>example</a> string</div>")
      'Another example string'
      """
  
output:     import re
      return re.sub(r'<[^>]+>', '', str)