Collection::toJson PHP Method

    public function toJson()
    {
        return json_encode($this->data);
    }

<?php

require_once 'Arr.php';
require_once 'Collection.php';
$foo = array('name' => 'haicheng', 'age' => '28');
$foo_collection = new Collection($foo);
echo $foo_collection->toJson();
$foo_collection->add('foo1', '1');
$foo_collection->add('foo2.foo1-1', '2');
echo $foo_collection->toJson();
var_dump($foo_collection->getIterator());