pub type PFNGLSECONDARYCOLOR3SEXTPROC = Option<unsafe extern "C" fn(red: GLshort, green: GLshort, blue: GLshort)>;
enum PFNGLSECONDARYCOLOR3SEXTPROC { None, Some(unsafe extern "C" fn(_: i16, _: i16, _: i16)), }
No value.
Some value of type T.
T