How can the reference of the v-for iteration be used as a parameter in Vue.js?

Question

I’m creating a TodoList where I have the editTodo() which will allow you to change an item in the list, but in the vi declaration which is passed as a parameter the reference todo which I use in the v-for and I got the doubt, why not use the array todos as a parameter and how the method can display this nickname or reference?

Part of the component:

<div v-for="(todo,index) in todos" :key="todo.id" class="todo-item">

<div class="todo-item-left">
 <div v-if="!todo.editing" class="todo-item-label" 
    @dblclick="editTodo(todo)">{{todo.title}}
 </div>
 <input v-else class="todo-item-edit" type="text" v-model="todo.title">

Method:

editTodo(todo){
    todo.editing=true
}