# --pin marks a key as pinned
$ pda set a@mp hello
$ pda meta a@mp --pin
  ok pinned a@mp
$ pda meta a@mp
  key: a@mp
  secret: false
  writable: true
  pinned: true
  expires: never

# --unpin clears the pinned flag
$ pda meta a@mp --unpin
  ok unpinned a@mp
$ pda meta a@mp
  key: a@mp
  secret: false
  writable: true
  pinned: false
  expires: never

# --pin and --unpin are mutually exclusive
$ pda meta a@mp --pin --unpin --> FAIL
FAIL cannot meta 'a@mp': --pin and --unpin are mutually exclusive