Syntax: Unique(vector<string> vs[, int Sort, int Occurrence, int sort2])
sort2 = 0 (default), no sorting by occurrence.
sort2 = 1, sort by occurrence, ascending.
sort2 = 2, sort by occurrence, descending.
For more details, please visit:
https://www.originlab.com/doc/LabTalk/guide/Getting-Started-with-LT