pub type PFNGLUNIFORM1UI64VARBPROC = Option<unsafe extern "C" fn(location: GLint, count: GLsizei, value: *const GLuint64)>;
enum PFNGLUNIFORM1UI64VARBPROC { None, Some(unsafe extern "C" fn(_: i32, _: i32, _: *const u64)), }
No value.
Some value of type T.
T