input: from typing import List
  
  def clean_html_tags(str_: str) -> 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><span>Hello, World!</span></div>")
      'Hello, World!'
      """
      clean_str = re.sub("<.*?>", "", str_)
      return clean_str
output:     import re