Function reduce

reduce<T, A>(
    source: Source<T>,
    reducer: (
        accumulator: Awaited<A>,
        value: T,
        context: OperatorContext,
    ) => Awaited<A> | PromiseLike<Awaited<A>>,
    initial: A,
    options?: ExecutionOptions,
): Promise<Awaited<A>>
Reduces values from source sequentially using reducer and returns the final accumulator after cleanup.

initial is awaited before opening source. If source is empty, the resolved initial value is returned. Object accumulators are passed by reference.
Type Parameters
- T
- A
Parameters
- source: Source<T>
- reducer: (
      accumulator: Awaited<A>,
      value: T,
      context: OperatorContext,
  ) => Awaited<A> | PromiseLike<Awaited<A>>
- initial: A
- options: ExecutionOptions = {}
Returns Promise<Awaited<A>>