docs: function reduce(accumulator, iterable, initializer = undefined) {
  
    if (initializer === undefined) {
      const iterator = (0, _iter.iter)(iterable);
      const first = iterator.next();
  
      if (first.done) {
        return undefined;
      }
  
      return (0, _reduce2._reduce)(accumulator, iterator, first.value);
    }
  
    return (0, _reduce2._reduce)(accumulator, iterable, initializer);
  }