css中flex-flow属性是什么

.flex-flow{

           display: flex;

           display: -webkit-flex;

           flex-flow: column-reverse wrap;

           width: 300px;

           height: 200px;

           margin: auto;

           background-color: red;

       }

       .flex{

           width: 60px;

           height: 60px;

           border: 1px #000000 solid;

           background-color: aqua;

           text-align: center;

           line-height: 60px;

           color: #ffffff;

       }