pub type Proc_MSPAppendData = Option<unsafe extern "C" fn(data: *mut c_void, dataLen: c_uint, dataStatus: c_uint) -> c_int>;
enum Proc_MSPAppendData { None, Some(unsafe extern "C" fn(_: *mut c_void, _: u32, _: u32) -> i32), }
No value.
Some value of type T.
T