import React from 'react';import PropTypes from 'prop-types';class Greeting extends React.Component {
render() {
return (Hello, {this.props.name}.
{this.props.children}
);
}}Greeting.propTypes = {
name: PropTypes.string, // must be a string
children: PropTypes.element.isRequired, // must be one element};class App extends React.Component {
render() {
return How do you do?;
}}export default App;