PetscSF Object: 4 MPI processes
  type: basic
  [0] Number of roots=6, leaves=2, remote ranks=2
  [0] 0 <- (3,2)
  [0] 2 <- (1,0)
  [1] Number of roots=4, leaves=3, remote ranks=2
  [1] 0 <- (0,2)
  [1] 2 <- (2,0)
  [1] 4 <- (0,4)
  [2] Number of roots=4, leaves=3, remote ranks=3
  [2] 0 <- (1,2)
  [2] 2 <- (3,0)
  [2] 4 <- (0,4)
  [3] Number of roots=4, leaves=3, remote ranks=2
  [3] 0 <- (2,2)
  [3] 2 <- (0,0)
  [3] 4 <- (0,4)
  [0] Roots referenced by my leaves, by rank
  [0] 1: 1 edges
  [0]    2 <- 0
  [0] 3: 1 edges
  [0]    0 <- 2
  [1] Roots referenced by my leaves, by rank
  [1] 0: 2 edges
  [1]    0 <- 2
  [1]    4 <- 4
  [1] 2: 1 edges
  [1]    2 <- 0
  [2] Roots referenced by my leaves, by rank
  [2] 0: 1 edges
  [2]    4 <- 4
  [2] 1: 1 edges
  [2]    0 <- 2
  [2] 3: 1 edges
  [2]    2 <- 0
  [3] Roots referenced by my leaves, by rank
  [3] 0: 2 edges
  [3]    2 <- 0
  [3]    4 <- 4
  [3] 2: 1 edges
  [3]    0 <- 2
  MultiSF sort=rank-order
## Data at multi-roots, to scatter to leaves
[0] 0: 1000 1200 1400 1401 1402
[1] 0: 2000 2200
[2] 0: 3000 3200
[3] 0: 4000 4200
## Scattered data at leaves
[0] 0: 4200 -1 2000 -1
[1] 0: 1200 -1 3000 -1 1400 -1
[2] 0: 2200 -1 4000 -1 1401 -1
[3] 0: 3200 -1 1000 -1 1402 -1