content: import React from 'react'
  import ReactDOM from 'react-dom'
  
  class App extends React.Component{
    constructor(props){
      super(props);
      this.state = { clickCount: props.initialCount}
    }
    addOne = () => {
      this.setState({ clickCount : this.state.clickCount + 1 });
    }
    subOne = () => {
      this.setState({ clickCount : this.state.clickCount - 1 });
    }
    render(){
      return (
        <div>
          <h1>Hi world</h1>
          <p>Click Count: {this.state.clickCount }</p>
          <button type="button" onClick={this.addOne}>+1</button>
          <button type="button" onClick={this.subOne}>-1</button>
        </div>
      )
    }
  }
  
  ReactDOM.render(<App initialCount={10}/>,document.getElementById('react-app'))
  