This will send to Map or clusterMap, depending on whether cl is provided.
Because they use different argument names for the main function
to call, leave that argument unnamed.
Map2(f, ..., cl = NULL)passed as f to Map or fun to clusterMap
passed to Map or clusterMap
A cluster object, passed to clusterMap
if (FALSE) {
a <- 1:5
Map2(a, f = function(x) x)
}