input: from typing import List
  
  def html_to_text(html_string: str) -> str:
      """
      Convert HTML code to plain text by removing HTML tags.
  
      >>> html_to_text('<p>Hello, <b>world</b>!</p>')
      'Hello, world!'
  
      >>> html_to_text('This is a test: <a href="example.com">link</a>')
      'This is a test: link'
      """
output:     import re
      return re.sub(r'<[^>]+>', '', html_string)