# luan:Html.luan - `Html.encode(s)`: escapes `<`, `>` and `"`. It escapes `&` only when it starts something that looks like an entity, so `&amp;` becomes `&amp;amp;` but a bare `a & b` is left alone, which browsers accept. It doesn't escape `'`, so use it only in text and in double-quoted attributes. Errors on nil.