$ ssh-add -h "scylla.example.org" \
          -h "cetus.example.org" \
          -h "scylla.example.org>charybdis.example.org" \
          -h "cetus.example.org>charybdis.example.org" \
          -h "charybdis.example.org>hydra.example.org" \
          ~/.ssh/id_ed25519

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