an style="color: #b22222;">(DO NOT trust the internal handles)</span>
  <span style="color: #a020f0;">call</span> <span style="color: #0000ff;">MPI_Comm_Group</span>(bridge_comm,gg,ierr)
  <span style="color: #a020f0;">call</span> <span style="color: #0000ff;">get_ranks_in_ref_comm</span>(dist1, ranks1)
  <span style="color: #a020f0;">call</span> <span style="color: #0000ff;">get_ranks_in_ref_comm</span>(dist2, ranks2)
  n1 = <span style="color: #a020f0;">size</span>(ranks1)
  n2 = <span style="color: #a020