Return the product of all values in an R vector. This wraps R's prod function.
i1 : x = RObject {2, 4, 6}
--error or time limit reached in conversion of output to net: type 'debugError()' to run it again; will try conversion to string
o1 = 2, 4, 6
o1 : RObject of type integer
i2 : product x
--error or time limit reached in conversion of output to net: type 'debugError()' to run it again; will try conversion to string
o2 = 48
o2 : RObject of type double