PayPal-PHP-SDK/lib/PayPal/Common/ArrayUtil.php

<?php
namespace PayPal\Common;

class ArrayUtil {
	
	/**
	 * 
	 * @param array $arr
	 * @return true if $arr is an associative array
	 */
	public static function isAssocArray(array $arr) {
		foreach($arr as $k => $v) {
			if(is_int($k)) {
				return false;
			}
		}
		return true;
	}
}