human
Solve the following python programming problem given the following code:
def getETreeBuilder(ElementTreeImplementation) : 
    ElementTree = <MASK> 
    ElementTreeCommentType = ElementTree.Comment ('asd').tag 
    class TreeWalker (_base.NonRecursiveTreeWalker) : 
        'Given the particular ElementTree representation, this implementation,
        to avoid using recursion, returns "nodes" as tuples with the following
        content:

        1. The current element

        2. The index of the element relative to its parent

        3. A stack of ancestor elements

        4. A flag "text", "tail" or None to indicate if the current node is a
           text node.
either the text or tail of the current element (1)
        ' 
        def getNodeDetails(self, node) : 
            if isinstance (node, tuple) : 
                (elt, key, parents, flag) = node 
                if (flag in ('text', 'tail')) : 
                    return (_base.TEXT, getattr (elt, flag)) 
else : 
                    node = elt 
if (not hasattr (node, 'tag')) : 
                node = node.getroot () 
if (node.tag in ('DOCUMENT_ROOT', 'DOCUMENT_FRAGMENT')) : 
                return (_base.DOCUMENT,) 
else : 
                if (node.tag == '<!DOCTYPE>') : 
                    return (_base.DOCTYPE, node.text, node.get ('publicId'), node.get ('systemId')) 
else : 
                    if (node.tag == ElementTreeCommentType) : 
                        return (_base.COMMENT, node.text) 
else : 
                        assert (type (node.tag) == text_type), type (node.tag) 
                        match = tag_regexp.match (node.tag) 
                        if match : 
                            (namespace, tag) = match.groups () 
else : 
                            namespace = None 
                            tag = node.tag 
attrs = OrderedDict () 
                        for (name, value) in list (node.attrib.items ()) : 
                            match = tag_regexp.match (name) 
                            if match : 
                                attrs [(match.group (1), match.group (2))] = value...
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
ElementTreeImplementation