This example demonstrates how to perform two tasks: customizing the hierarchical tree column's presentation and adding a formula to the group footers.
Notice the icons in the tree column. That icon is custom and is defined in the accountPresenter variable.
Presenters format column data. To use them, you define them and then add their names to the column definition's presenter option.
You can see this in the definition for the accountName field.
Also in this grid, you will notice aggregate totals in the accountName and total fields.
These are also added as formulas in the hierarchyFooter property in the column definition.