_.mixin({
    ldSanta: function (arr) {
        var ret = [],
            emailListCopy = _.assign(arr),
            receiver = {};
        _.times(_.size(emailListCopy), function (i) {
            receiver = arr[i];
            while (receiver === arr[i]) {
                receiver = _.first(_.shuffle(emailListCopy));
            }
            var pair = {
                'giver': arr[i],
                    'receiver': receiver
            };
            ret[i] = _.extend(pair);
            emailListCopy = _.reject(emailListCopy, function (item) {
                return item.name === receiver.name;
            });
        });
        return ret;
    }
});