public static function instance($prototype = null)
    {
        static $instance = null;
        if ($prototype !== null) {
            $instance = $prototype;
        } elseif ($instance === null || $prototype == true) {
            $instance = new HTMLPurifier_URISchemeRegistry();
        }
        return $instance;
    }
public static function instance($prototype = null)
    {
        static $instance = null;
        if ($prototype !== null) {
            $instance = $prototype;
        } elseif ($instance === null || $prototype == true) {
            $instance = new HTMLPurifier_URISchemeRegistry();
        }
        return $instance;
    }
public static function instance ( $ prototype = null ) { static $ instance = null ; if ( $ prototype !== null ) { $ instance = $ prototype ; } elseif ( $ instance === null || $ prototype == true ) { $ instance = new HTMLPurifier_URISchemeRegistry ( ) ; } return $ instance ; }
Retrieve sole instance of the registry.
@param HTMLPurifier_URISchemeRegistry $prototype Optional prototype to overload sole instance with,
or bool true to reset to default registry.
@return HTMLPurifier_URISchemeRegistry
@note Pass a registry object $prototype with a compatible interface and
the function will copy it and return it all further times.
Retrieve sole instance of the registry .