src/Metable/Hooks.php
public function __unsetHook()
    {
        return function ($next, $value, $args) {
            $key = $args->get('key');

            if ($this->hasMeta($key)) {
                return $this->setMeta($key, null);
            }

            return $next($value, $args);
        };
    }
public function __unsetHook()
    {
        return function ($next, $value, $args) {
            $key = $args->get('key');

            if ($this->hasMeta($key)) {
                return $this->setMeta($key, null);
            }

            return $next($value, $args);
        };
    }
Register hook on unset call.

@return \Closure