exports['delete'] = function deleteOne(Model, instance, next) {
	var collection = this.getCollection(Model),
		query = this.createPrimaryKeyQuery(instance.getPrimaryKey());

	if (!query) {
		return next(new Error('Invalid primary key for Delete One: ' + instance.getPrimaryKey()));
	}

	collection.remove(query, function deletedOne(err, removed) {
		/* istanbul ignore if */
		if (err) {
			return next(err);
		}
		if (removed != 1) {
			return next();
		}
		next(null, instance);
	});
};
