pub type PFNGLMATRIXMULT3X2FNVPROC = Option<unsafe extern "C" fn(matrixMode: GLenum, m: *const GLfloat)>;
enum PFNGLMATRIXMULT3X2FNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: *const f32)), }
No value.
Some value of type T.
T