vue如何在自定义组件中使用v-model

<!-- parent -->
<template>
<div class="parent">
  <p>我是父亲, 对儿子说： {{sthGiveChild}}</p>
  <Child @returnBack="turnBack" :give="sthGiveChild"></Child>
</div>
</template>
<script>
import Child from './Child.vue';
export default {
  data() {
    return {
      sthGiveChild: '给你100块'
    };
  },
  components: {
    Child
  },
  methods: {
    turnBack(val) {
      this.sthGiveChild = val;
    }
  }
}
</script>

<!-- child -->
<template>
<div class="child">
  <p>我是儿子，父亲对我说： {{give}}</p>
  <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" @click="returnBackFn">回应</a>
</div>
</template>
<script>
export default {
  props: {
    give: String
  },
  methods: {
    returnBackFn() {
      this.$emit('returnBack', '还你200块');
    }
  }
}
</script>

<!-- parent -->
<template>
<div class="parent">
  <p>我是父亲, 对儿子说： {{sthGiveChild}}</p>
  <Child v-model="sthGiveChild"></Child>
</div>
</template>
<script>
import Child from './Child.vue';
export default {
  data() {
    return {
      sthGiveChild: '给你100块'
    };
  },
  components: {
    Child
  }
}
</script>

<!-- child -->
<template>
<div class="child">
  <p>我是儿子，父亲对我说： {{give}}</p>
  <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" @click="returnBackFn">回应</a>
</div>
</template>
<script>
export default {
  props: {
    give: String
  },
  model: {
    prop: 'give',
    event: 'returnBack'
  },
  methods: {
    returnBackFn() {
      this.$emit('returnBack', '还你200块');
    }
  }
}
</script>

<!-- child -->
<template>
<div class="child">
  <p>我是儿子，父亲对我说： {{value}}</p>
  <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" @click="returnBackFn">回应</a>
</div>
</template>
<script>
export default {
  props: {
    value: String
  },
  methods: {
    returnBackFn() {
      this.$emit('input', '还你200块');
    }
  }
}
</script>

model: {
prop: 'someProp', // 注意，是prop，不带s。我在写这个速记的时候，多写了一个s，调试到怀疑人生
event: 'someEvent'
}
this.$emit('someProp', [returnValueToParent])