How to use the cjio.subset.process_appearance function in cjio

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"]
        cm2.update_bbox()
        return cm2

re.add(child)
            if "parents" in self.j['CityObjects'][theid]:
                for each in self.j['CityObjects'][theid]['parents']:
                    re.add(self.j['CityObjects'][each])

        
        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"]
        cm2.update_bbox()
        return cm2

#-- copy selected CO to the j2
        for theid in self.j["CityObjects"]:
            if exclude == False:
                if self.j["CityObjects"][theid]["type"] in lsCOtypes:
                    cm2.j["CityObjects"][theid] = self.j["CityObjects"][theid]
            else:
                if self.j["CityObjects"][theid]["type"] not in lsCOtypes:
                    cm2.j["CityObjects"][theid] = self.j["CityObjects"][theid]
        #-- 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"]
        cm2.update_bbox()
        return cm2