def clickable_link(link, display_str = 'link'):
  """Converts a link string into a clickable link with html tag.

  WARNING: This function is not safe to use for untrusted inputs since the
  generated HTML is not sanitized.

  Usage:
    df.style.format(clickable_link, subset=['col_name'])

  Args:
    link: A link string without formatting.
    display_str: What text the link should display.

  Returns:
    HTML-formatted link.

  """
  return f'<a href="{link}">{display_str}</a>'