type first
Returns an AsyncReducer that remembers the first input value.
example
await AsyncStream.from(Stream.range({ amount: 10 })).reduce(
AsyncReducer.first()
)
// => 0
Definition
first: {
<T>(): AsyncReducer<T, T | undefined>;
<T, O>(otherwise: AsyncOptLazy<O>): AsyncReducer<T, T | O>;
}