input: from typing import List
  
  
  def html_to_text(html_string: str) -> str:
      """ Convert an HTML string to plain text by stripping out all HTML tags.
      >>> html_to_text('<p>Hello, <b>world</b>!</p>')
      'Hello, world!'
      >>> html_to_text('<div><span>This is a test</span></div>')
      'This is a test'
      """
output:     import re
      return re.sub(r'<[^>]+>', '', html_string)