pub type PFNGLMULTITEXCOORD3HVNVPROC = Option<unsafe extern "C" fn(target: GLenum, v: *const GLhalf)>;
enum PFNGLMULTITEXCOORD3HVNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: *const u16)), }
No value.
Some value of type T.
T