input: from typing import List
  
  def convert_html_to_text(html: str) -> str:
      """
      Convert a given HTML string to plain text by removing all HTML tags.
      >>> convert_html_to_text('<p>Hello, <b>world</b>!</p>')
      'Hello, world!'
      >>> convert_html_to_text('<div><h1>Title</h1><p>This is a paragraph.</p></div>')
      'TitleThis is a paragraph.'
      >>> convert_html_to_text('<a href="https://example.com">Link</a>')
      'Link'
      """
      output = ''
      in_tag = False
      for char in html:
          if char == '<':
              in_tag = True
          elif char == '>':
              in_tag = False
          elif not in_tag:
              output += char
      return output
output:     output = ''
      in_tag = False
      for char in html:
          if char == '<':
              in_tag = True
          elif char == '>':
              in_tag = False
          elif not in_tag:
              output += char
      return output