1 pub enum Option<T> { 2 /// No value 3 None, 4 /// Some value `T` 5 Some(T), 6 } 7 8 impl<T> Default for Option<T> { 9 /// Returns None. 10 #[inline] default() -> Option<T>11 fn default() -> Option<T> { 12 None 13 } 14 } 15