input: 
  def html_to_text(html_string):
      """
      Convert an HTML string to plain text by stripping out all HTML tags.
      >>> html_to_text('<h1>Hello, World!</h1>')
      'Hello, World!'
      >>> html_to_text('<p>This is a <strong>test</strong> paragraph.</p>')
      'This is a test paragraph.'
      >>> html_to_text('This is plain text without any tags.')
      'This is plain text without any tags.'
      """
      output = ''
      in_tag = False
      for char in html_string:
          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_string:
          if char == '<':
              in_tag = True
          elif char == '>':
              in_tag = False
          elif not in_tag:
              output += char
      return output