Looping javascript array should not include zk defined function

<zk>
	<script type="text/javascript" defer="true"><![CDATA[
		var arr = ['0', '1', '2'], content = '';
		for (var i in arr) {
			content += i + '\n';
		}
		zk.Widget.$('$lbl').setValue(content);
	]]></script>
	Should only see 0, 1, 2 below:
	<separator />
	<label id="lbl" multiline="true"></label>
</zk>