Insertion Sort in Ruby

insertion-sort.rb

def insertion_sort(array) 
  result = array.dup

  def helper(array, index=0)
    return array if array[index] > array[index-1] || index == 0
    if array[index] < array[index-1]
      array[index], array[index-1] = array[index-1], array[index]
    end
    helper(array, index-1)  
  end
  
  for index in 1..result.size-1    
    result = helper(result, index)  
 end 

 result
end