pub type PFNGLUNIFORM3IPROC = Option<unsafe extern "C" fn(_: i32, _: i32, _: i32, _: i32)>;
enum PFNGLUNIFORM3IPROC { None, Some(unsafe extern "C" fn(_: i32, _: i32, _: i32, _: i32)), }
No value.
Some value of type T.
T