human
Solve the following python programming problem given the following code:
def __set__(self, document, element) : 
    def traverse(node) : 
        n = _Node () 
        n.tag = str (node.tag) 
        n.text = str (node.text) 
        n.tail = str (node.tail) 
        n.children = [traverse (n2) for n2 in node] 
        n.attributes = [_Attribute (str (k), str (v)) for (k, v) in node.attrib.items ()] 
        return n 
document._root = traverse (element.getroot ()) 
    document._element = document 

    
    

    Fix the buggy line: document._element = document
assistant
#Here is Python code to fix the buggy line: document.

document._element = element