pub type PFNGLTEXCOORD2FVERTEX3FVSUNPROC = Option<unsafe extern "C" fn(tc: *const GLfloat, v: *const GLfloat)>;
enum PFNGLTEXCOORD2FVERTEX3FVSUNPROC { None, Some(unsafe extern "C" fn(_: *const f32, _: *const f32)), }
No value.
Some value of type T.
T