pub type CK_C_GetInterfaceList = Option<unsafe extern "C" fn(arg1: *mut CK_INTERFACE, arg2: *mut CK_ULONG) -> CK_RV>;
enum CK_C_GetInterfaceList { None, Some(unsafe extern "C" fn(_: *mut CK_INTERFACE, _: *mut u32) -> u32), }
No value.
Some value of type T.
T