A = {1, 2, 3}
B = {3, 4, 5}
C = {1, 2, 3, 4, 5}
D = {2, 1, 3}

println( '2 is in A: ' + (2 in A) )
println( '4 is in A: ' + (4 in A) )
println( 'A union B: ' + A.union(B) )
println( 'A intersect B: ' + A.intersect(B) )
println( 'A difference B: ' + A.diff(B) )
println( 'A subset of B: ' + A.subsetOf(B) )
println( 'A subset of B: ' + A.subsetOf(C) )
println( 'A equal B: ' + (A == B) )
println( 'A equal D: ' + (A == D) )

S = set( A )

println( 'S (mutable version of A): ' + S )
S.add( 4 )
println( 'S with 4 added: ' + S )
println( 'S subset of C: ' + S.subsetOf(C) )
S.remove( 1 )
println( 'S after 1 removed: ' + S )