verify_md5 location?

[Norco]

Hey,
Im just wondering which page would the verify_md5 function be on? The has_password function is using it:

PHP Code:

/**
    * Takes a plain text or singly-md5'd password and returns the hashed version for storage in the database
    *
    * @param    string    Plain text or singly-md5'd password
    *
    * @return    string    Hashed password
    */
    function hash_password($password, $salt)
    {
        // if the password is not already an md5, md5 it now
        if ($password == '')
        {
        }
        else if (!$this->verify_md5($password))
        {
            $password = md5($password);
        }

        // hash the md5'd password with the salt
        return md5($password . $salt);
    } 


But I can't find the actual function which tells it what to do. Anyone know?