noop
----

noop
----
xxx

noop
----
----
xxx
----
----

noop
some input
----

noop
some input
----
xxx

duplicate
some input
----
yyy

duplicate
some input
----
----
yyy
----
----

duplicate-with-blank
some input
----

duplicate-with-blank
some input
----
----
some

expected
----
----

no-output
some input
----
zzz
