input: from typing import List
  
  def html_to_text(html_string: str) -> str:
      """ Converts a given HTML string to plain text by removing all HTML tags.
      >>> html_to_text("<h1>Hello, World!</h1>")
      'Hello, World!'
      >>> html_to_text("<p>This is a paragraph with a <a href='#'>link</a>.</p>")
      'This is a paragraph with a link.'
      """
output:     import re
      return re.sub(r'<[^>]+>', '', html_string)