pub type PFNGLMULTITEXCOORD2FARBPROC = Option<unsafe extern "C" fn(target: GLenum, s: GLfloat, t: GLfloat)>;
enum PFNGLMULTITEXCOORD2FARBPROC { None, Some(unsafe extern "C" fn(_: u32, _: f32, _: f32)), }
No value.
Some value of type T.
T