func main():
    >> t1 := @{10, 20, 30, 10}
    = @{10, 20, 30}
    >> t1.has(10)
    = yes
    >> t1.has(-999)
    = no

    >> t2 := {30, 40}

    >> t1.with(t2)
    >> {10, 20, 30, 40}

    >> t1.without(t2)
    >> {10, 20}

    >> t1.overlap(t2)
    >> {30}


    >> {1,2}.is_subset_of({2,3})
    = no
    >> {1,2}.is_subset_of({1,2,3})
    = yes
    >> {1,2}.is_subset_of({1,2})
    = yes
    >> {1,2}.is_subset_of({1,2}, strict=yes)
    = no

    >> t1.add_all(t2)
    >> t1
    = @{10, 20, 30, 40}
    >> t1.remove_all(t2)
    >> t1
    = @{10, 20}

    >> {3, i for i in 5}
    = {3, 1, 2, 4, 5}