Compile multiple less sources and concat results

less-concat.js

module.exports = function(sources, options, callback) {
        if ( ! callback) {
                callback = options;
                options = {};
        }

        options = _.defaults(options, LESS_OPTIONS);

        async.map(sources, function(source, callback) {
                compile(source, options, callback);
        }, function(err, results) {
                if (err) return callback(err);
                callback(null, results.join("\n"));
        });
};