title: How to make the aggregation function (aggFuncs) in a tree?
body: <p>I have a tree about like <a href="https://www.ag-grid.com/example-file-browser/#gsc.tab=0" rel="nofollow noreferrer">here</a>
  Can I use the aggregate function in nodes? To calculate the amounts of children. If so, how? Show on an example please with File Browser</p>