Реализация интерфейса и Fatal error

abstract public function unserialize(string $serialized);

    public function unserialize(string $serialized) {
        
    }

public function unserialize($serialized)

/**
 * (PHP 4, PHP 5, PHP 7)<br/>
 * Creates a PHP value from a stored representation
 * @link http://php.net/manual/en/function.unserialize.php
 * @param string $str <p>
 * The serialized string.
 * </p>
 * <p>
 * If the variable being unserialized is an object, after successfully
 * reconstructing the object PHP will automatically attempt to call the
 * __wakeup() member
 * function (if it exists).
 * </p>
 * <p>
 * unserialize_callback_func directive
 * <p>
 * It's possible to set a callback-function which will be called,
 * if an undefined class should be instantiated during unserializing.
 * (to prevent getting an incomplete object "__PHP_Incomplete_Class".)
 * Use your <i>php.ini</i>, <b>ini_set</b> or .htaccess
 * to define 'unserialize_callback_func'. Everytime an undefined class
 * should be instantiated, it'll be called. To disable this feature just
 * empty this setting.
 * </p>
 * </p>
 * @param array $options [optional] <p>
 * Any options to be provided to <b>unserialize</b>, as an
 * associative array.
 * </p>
 * <table>
 * Valid options
 * <tr valign="top">
 * <td>Name</td>
 * <td>Type</td>
 * <td>Description</td>
 * </tr>
 * <tr valign="top">
 * <td>allowed_classes</td>
 * <td>mixed</td>
 * <td>
 * Either an array of class names which should be
 * accepted, <b>FALSE</b> to accept no classes, or <b>TRUE</b> to accept all
 * classes. If this option is defined and
 * <b>unserialize</b> encounters an object of a class
 * that isn't to be accepted, then the object will be instantiated as
 * <b>__PHP_Incomplete_Class</b> instead.
 * Omitting this option is the same as defining it as <b>TRUE</b>: PHP
 * will attempt to instantiate objects of any class.
 * </td>
 * </tr>
 * </table>
 * @return mixed The converted value is returned, and can be a boolean,
 * integer, float, string,
 * array or object.
 * </p>
 * <p>
 * In case the passed string is not unserializeable, <b>FALSE</b> is returned and
 * <b>E_NOTICE</b> is issued.
 */
function unserialize(string $str, array $options = null) {}