How to use the react-chartjs-2.Chart.elements function in react-chartjs-2

import { Router } from 'react-router-dom';
import { createBrowserHistory } from 'history';
import { Chart } from 'react-chartjs-2';
import { ThemeProvider } from '@material-ui/styles';
import validate from 'validate.js';

import { chartjs } from './helpers';
import theme from './theme';
import 'react-perfect-scrollbar/dist/css/styles.css';
import './assets/scss/index.scss';
import validators from './common/validators';
import Routes from './Routes';

const browserHistory = createBrowserHistory();

Chart.helpers.extend(Chart.elements.Rectangle.prototype, {
  draw: chartjs.draw
});

validate.validators = {
  ...validate.validators,
  ...validators
};

export default class App extends Component {
  render() {
    return (

y + height
      );
      ctx.lineTo(x + radius, y + height);
      ctx.quadraticCurveTo(x, y + height, x, y + height - radius);
      ctx.lineTo(x, y + radius);
      ctx.quadraticCurveTo(x, y, x + radius, y);
    }
  }

  ctx.fill();
  if (borderWidth) {
    ctx.stroke();
  }
}

Chart.helpers.extend(Chart.elements.Rectangle.prototype, {
  draw
});

import React, {Component} from 'react';
import {Router} from 'react-router-dom';
import {createBrowserHistory} from 'history';
import {Chart} from 'react-chartjs-2';
import {ThemeProvider} from '@material-ui/styles';
import {chartjs} from './helpers';
import theme from './theme';
import './assets/scss/index.scss';
import Routes from './Routes';

const browserHistory = createBrowserHistory();

Chart.helpers.extend(Chart.elements.Rectangle.prototype, {
    draw: chartjs.draw
});


export default class App extends Component {

    render() {
        return (
            
                
                    
                
            
        );
    }
}