public function enrol_user(stdClass $instance, $userid, $roleid = null, $timestart = 0, $timeend = 0, $status = null, $recovergrades = null) {
        // no real enrolments here!
        return;
    }
public function enrol_user(stdClass $instance, $userid, $roleid = null, $timestart = 0, $timeend = 0, $status = null, $recovergrades = null) {
        // no real enrolments here!
        return;
    }
public function enrol_user ( stdClass $ instance , $ userid , $ roleid = null , $ timestart = 0 , $ timeend = 0 , $ status = null , $ recovergrades = null ) { // no real enrolments here! return ; }
Enrol a user using a given enrolment instance.

@param stdClass $instance
@param int $userid
@param null $roleid
@param int $timestart
@param int $timeend
@param null $status
@param null $recovergrades
Enrol a user using a given enrolment instance .