(ruby2.0)
irb(main):001:0> a = [1,2,3,4] => [1, 2, 3, 4] irb(main):002:0> b = [3,4,5,6] => [3, 4, 5, 6] irb(main):003:0> a & b => [3, 4] irb(main):004:0> a - b => [1, 2] irb(main):005:0> a | b => [1, 2, 3, 4, 5, 6] irb(main):019:0> c = [2,4,5,7] => [2, 4, 5, 7] irb(main):020:0> a - c => [1, 3]
