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Named Constants

psb_none_
  Generic no-op;
psb_root_
  Default root process for broadcast and scatter operations;
psb_nohalo_
  Do not fetch halo elements;
psb_halo_
  Fetch halo elements from neighbouring processes;
psb_sum_
  Sum overlapped elements
psb_avg_
  Average overlapped elements
psb_comm_halo_
  Exchange data based on the `halo_index` list;
psb_comm_ext_
  Exchange data based on the `ext_index` list;
psb_comm_ovr_
  Exchange data based on the `ovrlap_index` list;
psb_comm_mov_
  Exchange data based on the `ovr_mst_idx` list;