irb(main):022:0> dups = objects.all? {|object| !set.add?(object).nil?}
=> false
irb(main):023:0> objects = [1,2,3]
=> [1, 2, 3]
irb(main):024:0> ^C
irb(main):024:0> puts objects
1
2
3
=> nil
irb(main):025:0> dups = objects.all? {|object| !set.add?(object).nil?}
=> false