hash_leaves.rb

class Hash
  # {'x'=>{'y'=>{'z'=>1,'a'=>2}}}.leaves == [1,2]
  def leaves
    leaves = []

    each_value do |value|
      if value.is_a?(Hash)
        value.leaves.each{|l| leaves << l }
      elsif value.is_a?(Array)
        value.each{|l| leaves << l }
      else  
        leaves << value
      end
    end

    leaves
  end
end