03 - reversing an array.rb

O Reilly Ruby Cookbook source code

[1,2,3].reverse                     # => [3, 2, 1]
[1,[2,3,4],5].reverse               # => [5, [2, 3, 4], 1]
#---
a = [1,2,3]
a.reverse!
a                                  # => [3, 2, 1]
#---