title: how to sum nominal by _id method ? nested array
body: <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>let data = [{
      _id: '6081710355cebfa52c91f006',
      number: '081218302334',
      method: {
        deposite: 0,
        withdraw: 0,
        _id: '6081702cef267a9d14f08097',
        name: 'mandiri',
        __v: 0
      },
      nominal: 150000,
      member: '607ecffc03e9bd6a4dc24861',
      admin: 'dhimas hertianto',
      __v: 0
    },
    {
      _id: '6081711555cebfa52c91f007',
      number: '081218302334',
      method: {
        deposite: 0,
        withdraw: 0,
        _id: '60817032ef267a9d14f08098',
        name: 'bca',
        __v: 0
      },
      nominal: 17000,
      member: '607ecffc03e9bd6a4dc24861',
      admin: 'dhimas hertianto',
      __v: 0
    },
    {
      _id: '6081711555cebfa52c91f007',
      number: '081218302334',
      method: {
        deposite: 0,
        withdraw: 0,
        _id: '60817032ef267a9d14f08098',
        name: 'bca',
        __v: 0
      },
      nominal: 17000,
      member: '607ecffc03e9bd6a4dc24861',
      admin: 'dhimas hertianto',
      __v: 0
    }
  ]</code></pre>
  </div>
  </div>
  </p>
  <p>and expected :</p>
  <pre><code>[
    {
      id : ,
      name : mandiri,
      nominal : 15000
    },
    {
      id : ,
      name : bca,
      nominal : 34000
    },
  ]
  </code></pre>