///|
fn html_escape(text : String) -> String {
  let out = StringBuilder::new()
  for ch in text {
    match ch {
      '&' => out.write_string("&")
      '<' => out.write_string("<")
      '>' => out.write_string(">")
      '"' => out.write_string(""")
      '\'' => out.write_string("'")
      _ => out.write_char(ch)
    }
  }
  out.to_string()
}