code: function getIndexes(done, results) {
    var client = results.client;
    var ns = mongodbNS(results.namespace);
    client
      .db(ns.database)
      .collection(ns.collection)
      .indexes(function(err, indexes) {
        if (err) {
          done(err);
        }
        // add ns field to each index
        _.each(indexes, function(idx) {
          idx.ns = ns.ns;
        });
        done(null, indexes);
      });
  }
docs: get basic index information via `db.collection.indexes()`
  @param  {Function} done       callback
  @param  {object}   results    results from async.auto