Example of a "hack"

 1   class Array
 2     alias_method :concat, :old_concat
 3     def concat(*arrays)
 4       arrays.each { |array| old_concat(array) }
 5     end
 6   end
 7 
 8   a = [1, 2, 3]
 9   a.concat([1], [2], [3, 4])
10   p a #=> [1, 2, 3, 1, 2, 3, 4]