import {
reduce,
map,
filter,
flatMap,
flat,
fill,
entries,
keys,
values,
concat,
slice,
every,
some,
findIndex,
find,
indexOf,
includes,
forEach,
value,
asArray,
} from 'it-util'
function* gen() {
yield [10, 11, 12]
yield [13, 14, 15]
yield [16, 17, 18]
}
// Generator<[10, 11, 12, 13, 14, 15, 16, 17, 18]>
const flatGen = flat(gen())
// Generator<[1, 0, 1, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8]>
const flatMapGen = flatMap(flatGen, v => String(v).split('').map(Number))
// Generator<[3, 0, 3, 3, 3, 6, 3, 9, 3, 12, 3, 15, 3, 18, 3, 21, 3, 24]>
const mapGen = map(flatMapGen, v => v * 3)
// Generator<[0, 6, 12, 18, 24]>
const filterGen = filter(mapGen, v % 2 === 0)
// Generator<[0, 1, 2, 0, 6, 12, 18, 24, 3, 4, 5]>
const concatGen = concat(
[0, 1, 2],
filterGen,
[3, 4, 5]
)
// Generator<[1, 2, 0, 6, 12, 18, 24, 3]>
const sliceGen = slice(concatGen, 1, 9)
// Generator<[3, 3, 9, 21, 39, 63, 66]>
const reduceGen = reduce(sliceGen, (a, b) => a + b)
// 66
console.log(value(reduceGen))