All jobs are executed sequentially using the current R process in which
submitJobs is called.
submitJob blocks the session until the job has finished.
The main use of this
ClusterFunctions implementation is to test and debug programs on a local computer.
Listing jobs returns an empty vector (as no jobs can be running when you call this)
killJob is not implemented for the same reasons.
makeClusterFunctionsInteractive(external = FALSE, write.logs = TRUE, fs.latency = NA_real_)