What is the structre I should passs to filterState.addHierarchical('category', hierarchicalFilter)?

Hello there,
i have category attribute follows this structure

lvl1:“Women > Clothes”
lvl2:“Women > Clothes > Trousers”
i want to build a hierarchical menu like the one in instantSearch.js ,so i assume that I could use filterState.addHierarchical(‘category’, hierarchicalFilter) in order to achive the required but i didn’t know what the hierarchicalFilter could be…
any help would be appreciated
with thanks