class Aws::TreeHash

def digest
  hashes = @hashes
  digest = OpenSSL::Digest.new('sha256')
  until hashes.count == 1
    hashes = hashes.each_slice(2).map do |h1,h2|
      digest.reset
      if h2
        digest.update(h1)
        digest.update(h2)
        digest.digest
      else
        h1
      end
    end
  end
  hashes.first.bytes.map{|x| x.to_i.to_s(16).rjust(2, '0')}.join('')
end