input: 
  import re
  
  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_str = re.sub("<.*?>", "", str)
      return clean_str
  
output:     clean_str = re.sub("<.*?>", "", str)
      return clean_str