input: Write a python function to remove HTML tags from a string.
  assert remove_html_tags("<b>This is a bold string</b>") == "This is a bold string"
  assert remove_html_tags("<p>Paragraph</p><a href='#'>Link</a>") == "ParagraphLink"
  assert remove_html_tags("<div><span>Nested tags</span></div>") == "Nested tags"
output: def remove_html_tags(text):
      import re
      clean = re.compile('<.*?>')
      return re.sub(clean, '', text)