pub type LPALSOURCE3I = Option<extern "C" fn(source: ALuint, param: ALenum, value1: ALint, value2: ALint, value3: ALint)>;
enum LPALSOURCE3I { None, Some(extern "C" fn(_: u32, _: i32, _: i32, _: i32, _: i32)), }
No value.
Some value of type T.
T