start:Start {
    ports_exec = `["F","FF"]`;
}
end:End {
    ports_exec = `["F"]`;
}

p1:Print{
    custom = "Foo";
}

p2:Print{
    custom = "FooFoo";
}

p3:Print{
    custom = "FooFooFoo";
}

:Conn_exec (start -> p1) {from="F";to="in";}
:Conn_exec (p1 -> end) {from="out";to="F";}
:Conn_exec (start -> p2) {from="FF";to="in";}
:Conn_exec (p2 -> end) {from="out";to="F";}