php の call time pass by reference を見る奴

ebi.php

<?php

echo 'PHP Version: '.phpversion().PHP_EOL;
echo 'allow_call_time_pass_reference: '.(int)ini_get('allow_call_time_pass_reference').PHP_EOL;
echo '============================='.PHP_EOL.PHP_EOL;

function ref(&$arg)
{
  $arg = 'kani';
}

$ebi = 'ebi';
ref($ebi);
var_dump($ebi);

$ebi = 'ebi';
call_user_func('ref', $ebi);
var_dump($ebi);

$ebi = 'ebi';
call_user_func('ref', &$ebi);
var_dump($ebi);