fn revert_xml_encoding(text: &str) -> String {
  let mut out = String::with_capacity(text.as_bytes().len());
  let mut chars = text.chars();
  while let Some(c) = chars.next() {
    if c != '&' {
      out.push(c);
    } else {
      match chars.next().unwrap() {
        'l' => {
          assert_eq!(chars.next().unwrap(), 't');
          assert_eq!(chars.next().unwrap(), ';');
          out.push('<');
        }
        'g' => {
          assert_eq!(chars.next().unwrap(), 't');
          assert_eq!(chars.next().unwrap(), ';');
          out.push('>');
        }
        'a' => {
          assert_eq!(chars.next().unwrap(), 'm');
          assert_eq!(chars.next().unwrap(), 'p');
          assert_eq!(chars.next().unwrap(), ';');
          out.push('&');
        }
        other => panic!("{}", other),
      }
    }
  }
  out
}