input_stream: "INTS:ints"
output_stream: "DUBS:doubled"
output_stream: "QUADS:quadrupled"
output_stream: "OCTS:octupled"
node {
  calculator: "DubQuadTestSubgraph"
  input_stream: "INTS:ints"
  output_stream: "DUBS:doubled"
  output_stream: "QUADS:quadrupled"
}
node {
  calculator: "DoubleIntCalculator"
  input_stream: "quadrupled"
  output_stream: "octupled"
  # The following is to ensure we handle NULs correctly.
  input_stream_info {
    tag_index: ":0"  # 'quadrupled'
    back_edge: false  # The false boolean value is encoded as a zero byte.
  }
}