Gtk.TreeStore.prototype.append

function append(parent:Gtk.TreeIter):void {
    // Gjs wrapper for gtk_tree_store_append()
}

Appends a new row to tree_store. If parent is non-null, then it will append the new row after the last child of parent, otherwise it will append a row to the top level. iter will be changed to point to this new row. The row will be empty after this function is called. To fill in values, you need to call Gtk.set or Gtk.set_value.