pub type PFNGLTEXSTORAGE1DPROC = Option<unsafe extern "C" fn(_: u32, _: i32, _: u32, _: i32)>;
enum PFNGLTEXSTORAGE1DPROC { None, Some(unsafe extern "C" fn(_: u32, _: i32, _: u32, _: i32)), }
No value.
Some value of type T.
T