code: function checkForDisconnectedDevices(bigIp) {
          return bigIp.cluster.getCmSyncStatus()
              .then((response) => {
                  logger.silly('cmSyncStatus:', response);
  
                  const disconnected = response ? response.disconnected : [];
                  const hostnames = [];
                  const hostnamesToRemove = [];
  
                  // response is an object of two lists (connected/disconnected) from getCmSyncStatus()
                  if (disconnected.length > 0) {
                      logger.info('Possibly disconnected devices:', disconnected);
  
                      // get a list of hostnames still in the instances list
                      Object.keys(this.instances).forEach((instanceId) => {
                          if (this.instances[instanceId].hostname) {
                              hostnames.push(this.instances[instanceId].hostname);
                          }
                      });
  
                      // make sure this is not still in the instances list
                      disconnected.forEach((hostname) => {
                          if (hostnames.indexOf(hostname) === -1) {
                              logger.info('Disconnected device:', hostname);
                              hostnamesToRemove.push(hostname);
                          }
                      });
  
                      if (hostnamesToRemove.length > 0) {
                          logger.info('Removing devices from cluster:', hostnamesToRemove);
                          return bigIp.cluster.removeFromCluster(hostnamesToRemove);
                      }
                  }
                  return q();
              })
              .catch((err) => {
                  logger.warn('Could not get sync status');
                  return q.reject(err);
              });
      }
docs: Called with this bound to the caller