map.js

function* map(values, gf) {
  const result = [];
  for (let i = 0; i < values.length; i++) {
    result.push(yield* gf(values[i], i, values));
  }
  return result;
}

function* knockCodeHandler(preset) {
  while (true) {
    const input = yield* map(preset, function*() { return getCode(yield) });
    //..
  }
}