How to use the cjio.subset function in cjio

def get_subset_ids(self, lsIDs, exclude=False):
        #-- new sliced CityJSON object
        cm2 = CityJSON()
        cm2.j["version"] = self.j["version"]
        cm2.path = self.path
        if "transform" in self.j:
            cm2.j["transform"] = self.j["transform"]
        #-- copy selected CO to the j2
        re = subset.select_co_ids(self.j, lsIDs)
        if exclude == True:
            allkeys = set(self.j["CityObjects"].keys())
            re = allkeys ^ re
        for each in re:
            cm2.j["CityObjects"][each] = self.j["CityObjects"][each]
        #-- geometry
        subset.process_geometry(self.j, cm2.j)
        #-- templates
        subset.process_templates(self.j, cm2.j)
        #-- appearance
        if ("appearance" in self.j):
            cm2.j["appearance"] = {}
            subset.process_appearance(self.j, cm2.j)
        #-- metadata
        if ("metadata" in self.j):
            cm2.j["metadata"] = self.j["metadata"]