pub type PFNGLUNIFORM3FVARBPROC = Option<unsafe extern "C" fn(_: i32, _: i32, _: *const f32)>;
enum PFNGLUNIFORM3FVARBPROC { None, Some(unsafe extern "C" fn(_: i32, _: i32, _: *const f32)), }
No value.
Some value of type T.
T