input: from typing import List
  
  def convert_html_to_text(html_string: str) -> str:
      """ Convert a given HTML string to plain text, removing all HTML tags.
      >>> convert_html_to_text('<h1>Hello, World!</h1>')
      'Hello, World!'
      >>> convert_html_to_text('<p>This is a <strong>test</strong>.</p>')
      'This is a test.'
      """
output:     import re
      text = re.sub(r'<[^>]+>', '', html_string)
      return text