celbaz

{
    "AF": "Afghanistan",
    "DZ": "Algeria",
    "AS": "American Samoa",
    "AD": "Andorra",
    "AO": "Angola",
    "AI": "Anguilla",
    "AG": "Antigua & Barbuda",
    "AR": "Argentina",
    "AM": "Armenia",

celbaz

class Array

  def deep_dup
    self.map do |el|
      if !el.is_a? Array
        el
      elsif self.none? {|el| el.is_a? Array}
        el.map {|el2| el2}
      else
        el.deep_dup

celbaz

def subsets(array)
   result = [[]]
   array.each do |el|
     result.each_with_index do |curr, i|
      result << curr + [el] unless curr.include? el
    end
   end
   result
end