docs: function normalizeIds(ids) {
      if (_.isArray(ids)) {
        // remove any nesting of arrays - it is assumed that the resulting ids will be simple string or number values.
        ids = _.flatten(ids);
        // remove any duplicate ids.
        return _.uniq(ids);
      } else if (_.isString(ids) || _.isNumber(ids)) {
        // individual id - convert to array for consistency.
        return [ids];
      } else if (ids && ids.skipObjectRetrieval) {
        return ids;
      }
    }