pub type PFNGLTEXSCISSORINTELPROC = Option<unsafe extern "C" fn(target: GLenum, tlow: GLclampf, thigh: GLclampf)>;
enum PFNGLTEXSCISSORINTELPROC { None, Some(unsafe extern "C" fn(_: u32, _: f32, _: f32)), }
No value.
Some value of type T.
T