Compares JSON objects
        :param a:
        :param b:
        :return: difference object a vs b

def diff(a, b):
        """
        Compares JSON objects
        :param a:
        :param b:
        :return: difference object a vs b
        """
        delta = diff(a, b)
        if not a:
            return delta
        for item in delta:
            if isinstance(a[item], list):
                if delta[item] == []:
                    delta[item] = {JSONUtils.DIFF_DELETE : a[item]}
                elif isinstance(delta[item], dict):
                    for key in delta[item].keys():
                        if str(key) == JSONUtils.DIFF_DELETE:
                            delta_upd = {JSONUtils.DIFF_DELETE : []}
                            for i in delta[item][key]:
                                delta_upd[JSONUtils.DIFF_DELETE].append(a[item][i])
                                delta[item] = delta_upd
        return delta