code: function linkedIds(resource, linksKey) {
      return _.compact(_.flatten(_.map(resource, function(obj) {
        return obj.links && obj.links[linksKey];
      })));
    }
docs: Returns the id(s) to lookup from the 'links' section of the resource.
  
  @param {Object} The resource.
  @param {String} The link key.
  @api private