RAA - rand

Helper methods for Enumerable, Array, Hash, and String
that let you pick a random item or shuffle the order of items.

Examples with Array:

[1,2,3,4].pick
# => 2 (pick random element)

[1,2,3,4].shuffle
# => [2, 4, 1, 3] (return random-sorted version)

a = [1,2,3,4]
a.pick!
# => 3
a
# => [1,2,4] (remove the picked element)