content: import React, { Component } from 'react';
  import { connect } from 'react-redux';
  
  class BookDetail extends Component {
      render() {
          if(!this.props.book){
              return <div>Select a book to get started.</div>;
          }
  
          return (
              <div>
                  <h3>Details for:</h3>
                  <div>Title: {this.props.book.title}</div>
                  <div>Pages: {this.props.book.pages}</div>
              </div>
          );
      }
  }
  
  function mapStateToProps(state){
      return{
          book: state.activeBook
      };
  }
  
  export default connect(mapStateToProps)(BookDetail);