set_difference(s1, @rest...)
Return the set s1 without the elements of the sets ....
set_difference(#(1,2,3))
// #(1,2,3)
set_difference(#(1,2), #(2,3))
// #(1)
set_difference(#(1,2,3), #(1), #(1,4), #(3))
// #(2)
set_difference(#(1, 2, 3, 4), set_difference(#(1, 2, 3, 4), #(3, 5, 1, 6, 4)))
// #(3, 4, 1)