unicode_letter = /* a Unicode code point categorized as "Letter" */ .
unicode_digit  = /* a Unicode code point categorized as "Number, decimal digit" */ .
</pre>

<p>
In <a href="https://www.unicode.org/versions/Unicode8.0.0/">The Unicode Standard 8.0</a>,
Section 4.5 "General Category" defines a set of character categories.
Go treats all characters in any of the Letter categories Lu, Ll, Lt, Lm, or Lo

    * Document better how to handle exceptions and use error handlers.
    * Include `RequestValidationError` and `WebSocketRequestValidationError` (this last one will be useful once [encode/starlette#527](https://github.com/encode/starlette/pull/527) or equivalent is merged).
    * New documentation about exceptions handlers: