Get hash tree

const params = {
  from_ball: 'aEU1WiY9FQ9ihv9cKkX/EHWDxYYVaWYs2AL1yxyYZAQ=',
  to_ball: 'nOqDBwCVHy+bkBSRIgNlzcKR+EXlTC79aA62qT+Lcj0='
};
​
client.api.getHashTree(params, function(err, result) {
  console.log(result);
});

{
  balls: [
    {
      unit: 'c2teVop7xa1BmH1LPvytvOKU8HHTrprGWQw+uHlWPHo=',
      ball: 'ht1QP48paWg5hpjx+Nbd/DSRFT8WlbQKk9+Uum0/tso=',
      parent_balls: [Array]
    },
    {
      unit: 'tPbC6QLeweGuiGYRPsIhfd0TQWXWASYBJJUPGa9AOfw=',
      ball: 'ba5wFB+gewdRX6nSpxt6+Nt8PaRen4pLIYg3jC6EvIw=',
      parent_balls: [Array]
    },
    ...
  ]
}