How to use the yjs/dist/y.es6.extend function in yjs

import AceEditor from 'react-ace';
import 'brace/mode/markdown';
import 'brace/theme/tomorrow_night';
import SplitPane from 'react-split-pane';

import Y from 'yjs/dist/y.es6';
import yArray from 'y-array/dist/y-array.es6';
import yWebsocketsClient from 'y-websockets-client/dist/y-websockets-client.es6';
import yMemory from 'y-memory/dist/y-memory.es6';
import yText from 'y-text/dist/y-text.es6';

import verge from 'verge';

import WikiParser from './WikiParser';

Y.extend(yArray, yWebsocketsClient, yMemory, yText);

const aceRequire = brace.acequire;

const resizerMargin = 12;

export default class AppEnabledWikiEditorAce extends React.Component {
  constructor(props) {
    super();
    this.state = { text: props.defaultValue, hast: WikiParser.convertToCustomHast(WikiParser.parseToHast(props.defaultValue)), editorPercentage: 50 };
    this.handleResize = this.updateSize.bind(this);
    this.handleSplitResized = this.handleSplitResized.bind(this);
    this.handleEdit = this.handleEdit.bind(this);
    this.handleAppEdit = this.handleAppEdit.bind(this);
    this.AceRange = aceRequire('ace/range').Range;
  }
  componentWillMount() {

import 'codemirror/mode/markdown/markdown';
import SplitPane from 'react-split-pane';
import io from 'socket.io-client';
import ColorConvert from 'color-convert';

import Y from 'yjs/dist/y.es6';
import yArray from 'y-array/dist/y-array.es6';
import yWebsocketsClient from 'y-websockets-client/dist/y-websockets-client.es6';
import yMemory from 'y-memory/dist/y-memory.es6';
import yText from 'y-text/dist/y-text.es6';

import actual from 'actual';

import WikiParser from './WikiParser';

Y.extend(yArray, yWebsocketsClient, yMemory, yText);

const resizerMargin = 12;

class OtherClientCursor {
  constructor(id) {
    this.id = id;
    let hue = 0;
    for (let i = 0; i < id.length; i += 1) {
      hue *= 2;
      hue += id.charCodeAt(i);
      hue %= 360;
    }
    this.color = `#${ColorConvert.hsv.hex(hue, 100, 100)}`;
  }

  updateCursor(cursorPos, cm) {