const iterate = (genFunc) => {
  const generator = genFunc();
  const _void = ()=> undefined;

  const subscribe = (next, complete=_void , error=_void) => {
    const {value, done} = generator.next();
    if(!done){
      return Promise.resolve(value).then(next)
        .then(() => subscribe(next, complete, error))
        .catch(err => error(err))
    }
    else {
      return Promise.resolve(complete());
    }
  }
  return subscribe;
}