Preserve Comments During XML Parsing in Python 2.7+

CommentedTreeBuilder.py

#!/usr/bin/env python

from xml.etree import ElementTree

class CommentedTreeBuilder ( ElementTree.XMLTreeBuilder ):
    def __init__ ( self, html = 0, target = None ):
        ElementTree.XMLTreeBuilder.__init__( self, html, target )
        self._parser.CommentHandler = self.handle_comment
    
    def handle_comment ( self, data ):
        self._target.start( ElementTree.Comment, {} )
        self._target.data( data )
        self._target.end( ElementTree.Comment )

manipulate_xml.py

#!/usr/bin/env python

import xml.etree.ElementTree as ET
from CommentedTreeBuilder import CommentedTreeBuilder
parser = CommentedTreeBuilder()

if __name__ == '__main__':
    filename = "/opt/lucee/tomcat/conf/server.xml"
    
    # this is the important part: use the comment-preserving parser
    tree = ET.parse(filename, parser)
    
    # get the node to add a child to
    engine_node = tree.find("./Service/Engine")
    
    # add a node: Engine.Host
    host_node = ET.SubElement(
        engine_node,
        "Host",
        name="local.mysite.com",
        appBase="webapps"
    )
    # add a child to new node: Engine.Host.Context
    ET.SubElement(
        host_node,
        'Context',
        path="",
        docBase="/path/to/doc/base"
    )
    
    tree.write('out.xml')

Got the parser from Amaury Forgeot d'Arc

ElementTree.XMLTreeBuilder doesn't exists anymore in 3.5.2, it looks like it has been split, the class we have to inherit may be XMLParser.

class CommentedTreeBuilder ( ET.XMLParser ):
    def __init__ ( self, html = 0, target = None, encoding = None ):
        ET.XMLParser.__init__( self, html, target, encoding )
        self._parser.CommentHandler = self.handle_comment

    def handle_comment ( self, data ):
        self._target.start( ET.Comment, {} )
        self._target.data( data )
        self._target.end( ET.Comment )

However I get an error after trying this out:

    self._parser.CommentHandler = self.handle_comment
AttributeError: 'CommentedTreeBuilder' object has no attribute '_parser'

I don't understand why it does that because I saw ElementTree.py and the property is well defined...
I tried without the underscore, same thing.
Actually, none of the properties from XMLParser are available, and testing print(str(self.entity)) even crashes Python (Windows 10, 64 bits).
I wonder if I did anything wrong?

Edit:
This solved the problem for me.

# http://stackoverflow.com/questions/33573807/faithfully-preserve-comments-in-parsed-xml-python-2-7
class CommentedTreeBuilder(ET.TreeBuilder):
    def __init__(self, *args, **kwargs):
        super(CommentedTreeBuilder, self).__init__(*args, **kwargs)

    def comment(self, data):
        self.start(ET.Comment, {})
        self.data(data)
        self.end(ET.Comment)

#------------------------------------------------------------------------------
cparser = ET.XMLParser(target = CommentedTreeBuilder())
def read_xml_file(f):
    return ET.parse(f, parser=cparser)