code: public function bindTo($newthis, $newscope = 'static')
      {
          return new self(
              $this->closure->bindTo($newthis, $newscope),
              $this->serializer
          );
      }
docs: Clones the SerializableClosure with a new bound object and class scope.
  
  The method is essentially a wrapped proxy to the Closure::bindTo method.
  
  @param mixed $newthis  The object to which the closure should be bound,
  or NULL for the closure to be unbound.
  @param mixed $newscope The class scope to which the closure is to be
  associated, or 'static' to keep the current one.
  If an object is given, the type of the object will
  be used instead. This determines the visibility of
  protected and private methods of the bound object.
  
  @return SerializableClosure
  @link http://www.php.net/manual/en/closure.bindto.php