title: How to use in Vuejs3/setup method in mixins?
body: <p>In vuejs3 app I try to use in setup method in mixins, like I used in vuejs2
  My src/appMixin.js have:</p>
  <pre class="lang-js prettyprint-override"><code>import moment from 'moment-timezone'
  import { settingsAwesomeFontLabels } from './app.settings.js'
      
  export default {
    
    methods: {
    
      getClone: function (obj) {
        let copy = JSON.parse(JSON.stringify(obj))
        return copy
      },
  
    }
  }   
  </code></pre>
  <p>and in my vue file :</p>
  <pre class="lang-js prettyprint-override"><code>import appMixin from '@/appMixin'
  import app from './../../App.vue' // eslint-disable-line
  import axios from 'axios' // eslint-disable-line
  
  // ...
  
    setup () {
      function loadCategories() {
        isPageLoaded = false
        let credentials = getClone(credentialsConfig)
        credentials.headers.Authorization = 'Bearer ' + currentLoggedUserToken.value
  
            // ...
  </code></pre>
  <p>With getClone method I want to get credentialsConfig from settings.js file
  and modify headers with token of current login.
  But in console where I run command</p>
  <pre class="lang-sh prettyprint-override"><code>$ yarn run serve
  </code></pre>
  <p>I see error :</p>
  <pre><code>/mnt/_work_sdb8/wwwroot/lar/VApps/yt3/src/admin/categories/list.vue
    234:27  error  'getClone' is not defined  no-undef
  </code></pre>
  <p>and error in the broswer's console:</p>
  <pre><code>list.vue?c790:233 Uncaught (in promise) ReferenceError: getClone is not defined
  </code></pre>
  <p>I suppose because of error in console</p>
  <p>Which is correct way to export/import getClone into setup method?</p>
  <p>Thanks!</p>