pub type PWriteWriteProc = Option<unsafe extern "C" fn(arg1: *mut vlVoid, arg2: vlUInt, arg3: *mut vlVoid) -> vlUInt>;
pub enum PWriteWriteProc { None, Some(unsafe extern "C" fn(*mut c_void, u32, *mut c_void) -> u32), }
No value.
Some value of type T.
T