<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_from_xmlnode(self, element):
 """Load ui definition from xml.etree.Element node."""

        if self.tree is None:
            root = ET.Element('interface')
            root.append(element)
            self.tree = tree = ET.ElementTree(root)
            self.root = tree.getroot()
            self.objects = {}
            # ET.dump(tree)
        else:
            # TODO: append to current tree
            pass