pub type PFNGLVERTEXATTRIBL1I64VNVPROC = Option<unsafe extern "C" fn(index: GLuint, v: *const GLint64EXT)>;
enum PFNGLVERTEXATTRIBL1I64VNVPROC { None, Some(unsafe extern "C" fn(_: u32, _: *const i64)), }
No value.
Some value of type T.
T