# --readonly marks a key as read-only
$ pda set a@mro hello
$ pda meta a@mro --readonly
  ok made readonly a@mro
$ pda meta a@mro
  key: a@mro
  secret: false
  writable: false
  pinned: false
  expires: never

# --writable clears the read-only flag
$ pda meta a@mro --writable
  ok made writable a@mro
$ pda meta a@mro
  key: a@mro
  secret: false
  writable: true
  pinned: false
  expires: never

# --readonly and --writable are mutually exclusive
$ pda meta a@mro --readonly --writable --> FAIL
FAIL cannot meta 'a@mro': --readonly and --writable are mutually exclusive