Fibonnaci in PHP using yield

Fibonnaci.php

function getFibonacci()
{
    $i = 0;
    $k = 1; //first fibonacci value
    // yield $k;
    while(true)
    {
        $k = $i + $k;
        $i = $k - $i;
        yield $k;        
    }
}

 $y = 0;    
foreach(getFibonacci() as $k)
{
    echo $k  . "<br/>";
    $y++;    
    if($y > 30)
    {
        break; // infinite loop prevent
    }
}