setunorderedno duplicated elements {" "" "" "alternative set([sequence]required for empty sets constant sets frozenset([sequence] empty setempty frozenset(subsets issubset(ts < strict subsets supersets issuperset(ts > strict supersets unions union(ts intersections intersection(ts differences difference(ts symmetric differences symmetric_difference(ts copys copy(as with sequencesthe following worksx in len(sfor in add(xs remove(xmember of the helmholtz association slide