pub type PFNGLNORMALSTREAM3BATIPROC = Option<unsafe extern "C" fn(stream: GLenum, x: GLbyte, y: GLbyte, z: GLbyte)>;
enum PFNGLNORMALSTREAM3BATIPROC { None, Some(unsafe extern "C" fn(_: u32, _: i8, _: i8, _: i8)), }
No value.
Some value of type T.
T