docs: def html_for_cgi_argument(argument, form):
      """Returns an HTML snippet for a CGI argument.
  
      Args:
          argument: A string representing an CGI argument name in a form.
          form: A CGI FieldStorage object.
  
      Returns:
          String HTML representing the CGI value and variable.
      """
      value = form[argument].value if argument in form else None
      return KEY_VALUE_TEMPLATE.format(argument, value)