Change selected tab on click event

I'm new in Vuejs and I want to change the selected tab of nav on click event I trying using function but console throw an error:

vue.runtime.global.js:8392 Uncaught TypeError: _ctx.changeTab is not a function

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What I want to do, is to on @click event run a function that change selected tab and show content depending on the selected tab in a single paragraph element

Code:

<template>
  <div>
    <div class="sm:hidden">
      <label for="tabs" class="sr-only">Select a tab</label>
      <select id="tabs" name="tabs" class="block w-full focus:ring-indigo-500 focus:border-indigo-500 border-gray-300 rounded-md">
        <option v-for="tab in tabs" :key="tab.name" :selected="tab.current">{{ tab.name }}</option>
      </select>
    </div>
    <div class="hidden sm:block">
     <nav class="flex space-x-4" aria-label="Tabs" :class="bg-gray-600">
        <a v-for="tab in tabs" @click="changeTab(tab)"  :key="tab.name" :href="tab.href" :class="[tab.current ? 'bg-purple-700 text-white' : 'text-purple-700 hover:text-gray-700', 'px-12 py-2 font-medium text-sm rounded-full font-bold text-lg']" >
          {{ tab.name }}
        </a>
      </nav>
    </div>
  </div>
</template>

<script>
const tabs = [
  { id: 1 , name: 'LOREM', href: '#test1', current: false },
  { id: 2, name: 'IPSUM', href: '#test2', current: false },
  { id: 3, name: 'PDF', href: '#test3', current: true },
]
export default {
  setup() {
    return {
      tabs,
    }
    
     function changeTab(selectedTab){
      let test = this.tabs.find(selectedTab.id);
       
       console.log(test)
    }
  },
}
</script>


<style>
  nav {
    width: max-content; 
    display: flex;
    gap: 20px; 
    background: #E5E5E5; 
    border-radius: 20px; 
}
</style>

How can I achieve this? Regards