Function useReducer

docs/external/js/react.development.js:1585–1588

(reducer, initialArg, init)

    return dispatcher.useState(initialState);
  }
  function useReducer(reducer, initialArg, init) {
    var dispatcher = resolveDispatcher();
    return dispatcher.useReducer(reducer, initialArg, init);
  }
  function useRef(initialValue) {
    var dispatcher = resolveDispatcher();
    return dispatcher.useRef(initialValue);