code: function getAssociations(instance, ids, callback) {
    instance.db.find({ _id: { $in: ids } }, function(err, associations) {
      for(var cAssociation = 0; cAssociation < associations.length;
          cAssociation++) {
        associations[cAssociation].deviceId = associations[cAssociation]._id;
      }
      callback(err, associations);
    });
  }
docs: Retrieve from the database the associations of the given ids
  @param {Object} instance The given Chickadee instance.
  @param {Array} ids The given ids.
  @param {function} callback Function to call on completion.