Consume a 2d array in a "spiral"

spiral.rb

#!/usr/bin/env ruby

def spiral(array,ans=[])
  return ans unless array.any?
  ans += array.shift
  spiral(array.transpose.reverse, ans)
end

array = [
  [1,2,3,1],
  [4,5,6,4],
  [7,8,9,7],
  [7,8,9,7]
]

puts spiral(array).inspect