小技ネタ - Rubyの配列で、重複する要素をひとつにする。

a = ["x","y","x","z","y","x"]

があったときに、

a |= []

とする。

[taskapp@localhost]$ irb
irb(main):001:0> a = ["x","y","x","z","y","x"]
=> ["x", "y", "x", "z", "y", "x"]
irb(main):002:0> a |= []
=> ["x", "y", "z"]
irb(main):003:0>