pub type PFNGLRELEASEKEYEDMUTEXWIN32EXTPROC = Option<unsafe extern "C" fn(memory: GLuint, key: GLuint64) -> GLboolean>;
enum PFNGLRELEASEKEYEDMUTEXWIN32EXTPROC { None, Some(unsafe extern "C" fn(_: u32, _: u64) -> u8), }
No value.
Some value of type T.
T