pub type cookie_read_function_t = Option<unsafe extern "C" fn(_: *mut c_void, _: *mut i8, _: usize) -> i64>;
enum cookie_read_function_t { None, Some(unsafe extern "C" fn(_: *mut c_void, _: *mut i8, _: usize) -> i64), }
No value.
Some value of type T.
T