code: def tree_to_xml(self):
          
  
          # Need to remove filter or hidden items will not be saved.
          self.filter_remove(remember=True)
  
          tree = self.treeview
          root = ET.Element('interface')
          items = tree.get_children()
          for item in items:
              node = self.tree_node_to_xml('', item)
              root.append(node)
  
          # restore filter
          self.filter_restore()
  
          return ET.ElementTree(root)
docs: Traverses treeview and generates a ElementTree object