input_stream: "INTS:ints"
output_stream: "DUBS:doubled"
output_stream: "QUADS:quadrupled"
node {
  calculator: "DoubleIntCalculator"
  input_stream: "ints"
  output_stream: "doubled"
}
node {
  calculator: "DoubleIntCalculator"
  input_stream: "doubled"
  output_stream: "quadrupled"
}