pub type PSECURE_MEMORY_CACHE_CALLBACK = Option<unsafe extern "system" fn(Addr: PVOID, Range: SIZE_T) -> BOOLEAN>;
enum PSECURE_MEMORY_CACHE_CALLBACK { None, Some(unsafe extern "system" fn(_: *mut c_void, _: usize) -> u8), }
No value.
Some value of type T.
T