public function toUsers($ids)
    {
        if (!is_array($ids)) {
            $ids = [$ids];
        }

        $this->externalUserIds = $ids;
        return $this;
    }
public function toUsers($ids)
    {
        if (!is_array($ids)) {
            $ids = [$ids];
        }

        $this->externalUserIds = $ids;
        return $this;
    }
public function toUsers ( $ ids ) { if ( ! is_array ( $ ids ) ) { $ ids = [ $ ids ] ; } $ this -> externalUserIds = $ ids ; return $ this ; }
Set the external user ids to send to.

@param array|mixed $ids

@return NotificationBuilder

@see https://www.appboy.com/documentation/REST_API/#external-user-id
Set the external user ids to send to .