can i load another model inside model ?

[eluser]Mario "St.Peter" Valentino[/eluser]
hello all,

i wanna ask something about model. i have 2 model : level_model and user_model

Code:

// This is Level Model
Class Level_model extends CI_Model
{
    public function __construct()
    {
        parent::__construct();
    }

    public function level_data()
    {
        //code goes here
    }
}

// This is User Model
class USer_model extends CI_Model
{
    public function __construct()
    {
        parent::__construct()
    }

    public function user_data()
    {
       //code goes here
    }
}

i wanna make sure. can i load user model inside level model or vice versa ?
how to do it ?

please help me. Thanks