Recursion Steam

<?php
class SteamFriendFinder
{
    private $players = array();
    private $handle = null;
    private $apiKey = "XXXXXXXXXXX";

    public function __construct()
    {
        $this->handle = fopen("steam.txt","a+");
    }

    public function getFriends($id,$level = 0)
    {
        $f = @file_get_contents("http://api.steampowered.com/ISteamUser/GetFriendList/v0001/?key=".$this->apiKey."&steamid=".$id."&relationship=friend");

        if ($f){
        $arr = json_decode($f);

        foreach($arr->friendslist->friends as $friend)
        {
            $str = null;

            for ($i=0;$i<$level;$i++)
            {
            $str .= '.';
            }

            if (!isset($this->players[(string)$friend->steamid]))
            {
                $str .= $this->getUsernameById((string)$friend->steamid);

            echo $str."\n";
            fwrite($this->handle,$str."\r\n");

            $this->players[(string)$friend->steamid] = $friend;
            $this->getFriends((string)$friend->steamid,$level+1);

            }

        }
        }
    }

    public function getUsernameById($id)
    {
        $f = file_get_contents("http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=".$this->apiKey."&steamids=".$id);

        $arr = json_decode($f);
        return $arr->response->players[0]->personaname;

    }
}

$sff = new SteamFriendFinder();
$sff->getFriends("76561198027123396");
?>