The return array consists of the following values:
(
[imported] => (int),
[unchanged] => (int),
[newuserids] => (int),
[newsubkeys] => (int),
[secretimported] => (int),
[secretunchanged] => (int),
[newsignatures] => (int),
[skippedkeys] => (int),
[fingerprint] => (string)
)
When invalid content is passed, all values, even skippedkeys, is 0. The fingerprint value does not exist then.