content: //从react模块中引入React对象
  import React from 'react';
  //声明一个组件的子类并继承React.Component父类
  export default class PanelHead extends React.Component{
    render(){
        return (
            <div className="panel-heading">
                {this.props.content}
            </div>
        )
    }
  }
  
  