function transformFieldValue (field, item, options) {
	var transform = typeof field.options.toCSV === 'string'
		? listToArray(field.options.toCSV)
		: field.options.toCSV;
	if (typeof transform === 'function') {
		return transform.call(item, field, options);
	}
	if (Array.isArray(transform)) {
		var value = item.get(field.path);
		if (transform.length === 1) {
			return value[transform[0]];
		} else {
			return _.pick(value, transform);
		}
	}
	return field.format(item);
}
Applies option field transforms to get the CSV value for a field