What's a valid function signature for funSig?
funSig(() -> System.out.println());
What's a valid function signature for funSig?
funSig(() -> System.out.println());
A Runnable would work,
It matches a void return and no params.
Runnable runnable = () -> System.out.println();
And obviously it doesn't need to be Runnable, any Functional Interface that matches the signature will do.