<body>
    <div id="app">
      <ul is="transition-group">
        <li v-for="user in users" class="user" :key="user['.key']">
          <span>{{user.name}} - {{user.email}}</span>
          <button v-on:click="removeUser(user)">X</button>
        </li>
      </ul>
      <form id="form" v-on:submit.prevent="addUser">
        <input v-model="newUser.name">
        <input v-model="newUser.email">
        <input type="submit" value="Add User">
      </form>
      <ul class="errors">
        <li v-show="!valida