can be (){yield();} mark as @trusted?

[ikod]

Hello,

I have very short function with only Fiber.yield() inside it, 
like:

void f1() {
     yield();
}

This function is called inside @safe function f2:

void f2() @safe {
     f1();
}

Can f1 be marked as @trusted so that I can keep @safe for the 
whole hierarchy of calls?

Thanks!