Yield?

a part of aws-sdk.rb

      # Yields once for each key pair in your account.
      # @return [nil]
      def each &block
        response = filtered_request(:describe_key_pairs)
        response.key_set.each do |kp|
          yield(KeyPair.new(kp.key_name,
                            :fingerprint => kp.key_fingerprint,
                            :config => config))
        end 
        nil 
      end