input: Write a function to convert an HTML string to plain text without using any libraries. If an HTML tag is encountered, it should be ignored, and all text content outside of the tags should be concatenated into a single string. Return the resulting plain text string.
  
  def html_to_text(html_string):
      output = ''
      in_tag = False
      for char in html_string:
          if char == '<':
              in_tag = True
          elif char == '>':
              in_tag = False
          elif in_tag == False:
              output += char
      return output
  
  assert html_to_text("<h1>Hello</h1> World")=="Hello World"
  assert html_to_text("<p>This is a <b>bold</b> statement.</p>")=="This is a bold statement."
  assert html_to_text("<div><p>One</p><p>Two</p></div>")=="OneTwo"
  assert html_to_text("<title>Title</title><body>Body</body>")=="TitleBody"
  assert html_to_text("<a href='example.com'>Link</a>")=="Link"
output: def html_to_text(html_string):
      output = ''
      in_tag = False
      for char in html_string:
          if char == '<':
              in_tag = True
          elif char == '>':
              in_tag = False
          elif in_tag == False:
              output += char
      return output