source a 0 b 0
source a 1 b 10
source a 2 b 20
source a 3 b 30
source a 4 b 40
  sink a 0 b 0
  sink a 1 b 10
  sink a 2 b 20
  sink a 3 b 30
  sink a 4 b 40
source a 0 b 0
  sink a 0 b 0
source a 1 b 10
  sink a 1 b 10
source a 2 b 20
  sink a 2 b 20
source a 3 b 30
  sink a 3 b 30
source a 4 b 40
  sink a 4 b 40