PetscSF Object: sfA0 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=0, remote ranks=0
  MultiSF sort=rank-order
PetscSF Object: sfA1 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=1, remote ranks=1
  [0] 1 <- (0,0)
  MultiSF sort=rank-order
PetscSF Object: sfA2 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=1, remote ranks=1
  [0] 0 <- (0,0)
  MultiSF sort=rank-order
PetscSF Object: sfB 1 MPI process
  type: basic
  [0] Number of roots=2, leaves=2, remote ranks=1
  [0] 100 <- (0,0)
  [0] 101 <- (0,1)
  MultiSF sort=rank-order
PetscSF Object: PetscSFCompose(sfA0, sfB) 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=0, remote ranks=0
  MultiSF sort=rank-order
PetscSF Object: PetscSFCompose(sfA1, sfB) 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=1, remote ranks=1
  [0] 101 <- (0,0)
  MultiSF sort=rank-order
PetscSF Object: PetscSFCompose(sfA2, sfB) 1 MPI process
  type: basic
  [0] Number of roots=1, leaves=1, remote ranks=1
  [0] 100 <- (0,0)
  MultiSF sort=rank-order