function RadioGroupFactory(sources: any, props$: Observable<RadioGroupProps>,
                        children: Array<RadioButton>): CycleDomComponent {
  const childrenDOMs: any[] = [];
  const childrenValues: Observable<any>[] = [];
  //TODO: allow other kinds of children?
  for (let childRadio of children) {
    // TODO: maybe remove RadioButton interface if I can make value$ compile using CycleDomComponent
    // interface
    childrenValues.push(childRadio.value$);
    childrenDOMs.push(childRadio.DOM);
  }

  const itemMouseClick$ = Observable.just('RadioFirst');
  const vtree$ = props$.map( (props) => {

    const $radioGroupSelectedValue = Observable.combineLatest(childrenValues, (...values) => {
      return { itemMouseClick$ };
    }).startWith(props.value)
      .do(x => console.log('radioGroupSelectedValue ' + x));

    const className = classNames('radioGroup', props.className);

    return (
      div( { props: { className }, attrs: { 'data-cycle-ui': 'radio-group' } },
        childrenDOMs
      )
    );
  });

  return {
    DOM: vtree$,
  };

}

 let main = () => ({
   bot: $.from([
     $.just(sendChatAction(
       { chat_id: GROUP_ID, action: 'typing' },
       {}))
   ])
 })