$ pda set existing@idr keep-me
$ pda set other@idr also-keep
$ fecho dumpfile {"key":"new","value":"hello","encoding":"text"}
$ pda import idr --drop --file dumpfile
  ok restored 1 entries into @idr
$ pda get new@idr
hello
$ pda get existing@idr --> FAIL
FAIL cannot get 'existing@idr': no such key