-- source --
first
second
//copy:start dest foo
third
fourth
//copy:stop
fifth
//copy:start dest bar
sixth
//copy:stop
seventh
-- dest --
line1
//copy:sink bar
line2
//copy:sink foo
-- want --
line1
//copy:sink bar from source
// DO NOT MODIFY below vvvv
sixth
// DO NOT MODIFY above ^^^^
//copy:endsink bar
line2
//copy:sink foo from source
// DO NOT MODIFY below vvvv
third
fourth
// DO NOT MODIFY above ^^^^
//copy:endsink foo