pub type PFNGLGETFRAGMENTLIGHTFVSGIXPROC = Option<unsafe extern "C" fn(light: GLenum, value: GLenum, data: *mut GLfloat)>;
enum PFNGLGETFRAGMENTLIGHTFVSGIXPROC { None, Some(unsafe extern "C" fn(_: u32, _: u32, _: *mut f32)), }
No value.
Some value of type T.
T