Which statements are valid? $($Choose two$)$

DoubleConsumer cube $=$ x $->$ x$*$x$*$x;

Function hello $=()->$ "Hello";

BiPredicate add $=($x$,$ y$)->$ x $+$ y;

BiPredicate test $=($x$,$ y$)->$ x $==$ y;

Supplier hello $=()->$ "Hello";