pub type PFNGLMULTITEXCOORD3HNVPROC = Option<unsafe extern "C" fn(target: GLenum, s: GLhalf, t: GLhalf, r: GLhalf)>;
enum PFNGLMULTITEXCOORD3HNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: u16, _: u16, _: u16)), }
No value.
Some value of type T.
T