In WPF: Children.Remove or Children.Clear doesn't free objects

>>> for ev, elem in etree.iterparse(xml):
       print elem

<Element b at 0x38fe320>
<Element d at 0x38fe0f0>
<Element c at 0x38fe2d0>
<Element a at 0x38fe190>
<Element z at 0x38fe230>
<Element a at 0x38fe3c0>
<Element root at 0x2df48c0>

for ev, elem in etree.iterparse(xml, events=('start',)):
    ...

found = False
for event, elem in etree.iterparse(source, events=('start', 'end')):
    if event == 'start':
        if elem.attrib.get('id') == elem_id:
            found = True
    else:
        if elem.attrib.get('id') == elem_id:
            return _get_info(elem)
        if not found:
            elem.clear()

function cacheForm(agency) {
    // GET my object from agency vm
    var agency = ko.toJS(agency);

    var s = YUI().use("json-stringify", function (Y) {    
        var jsonStrAgency = Y.JSON.stringify(agency, ["activities", "agencyName", "agencyID", "campaignBillings", "category", "declaredBillings", "immediateParent", "numberOfEmployees", "ultimateParent", "uRL"]); // Use an array of acceptable object key names as a whitelist.
        var jsonStrOffices, jsonStrContacts;

        for (i in agency.offices) {
            jsonStrOffices = Y.JSON.stringify(agency.offices, ["address1", "address2", "address3", "address4", "address5", "agencyID", "faxNumber", "officeID", "postCode", "telephoneNumber"]);

        for (ii in agency.offices[i].contacts) {
                    jsonStrContacts = Y.JSON.stringify(agency.offices[i].contacts, ["agencyID", "emailAddress", "firstName", "jobName", "officeID", "personID", "surName", "title"]);
            }
        }

        localStorage.setItem('Agency', jsonStrAgency);
        localStorage.setItem('Offices', jsonStrOffices);
        localStorage.setItem('Contacts', jsonStrContacts);
    });
}

 var s = YUI().use("json-stringify", function (Y) {  

<script src="http://yui.yahooapis.com/3.11.0/build/yui/yui-min.js"></script>

define(['services/datacontext'], function (dataContext) {
    var initialized = false;
    var agency;

    if (localStorage.Agency && localStorage.Offices && localStorage.Contacts) {
        var objAgency = new Object(ko.mapping.fromJSON(localStorage.getItem('Agency')));
        var objOffices = new Object(ko.mapping.fromJSON(localStorage.getItem('Offices')));
        var objContacts = new Object(ko.mapping.fromJSON(localStorage.getItem('Contacts')));

        objAgency.offices = objOffices;
        objAgency.offices._latestValue[0].contacts = objContacts;


        agency = ko.observableArray([ko.mapping.fromJS(objAgency)]);
        ko.applyBindings(agency);

        initialized = true;

    }
    else {
        agency = ko.observableArray([]);
    }

define(['services/datacontext'], function (dataContext) {
    var initialized = false;
    var agency;

    if (localStorage.Agency && localStorage.Offices && localStorage.Contacts) {
        var objAgency = new Object(ko.mapping.fromJSON(localStorage.getItem('Agency')));
        var objOffices = new Object(ko.mapping.fromJSON(localStorage.getItem('Offices')));
        var objContacts = new Object(ko.mapping.fromJSON(localStorage.getItem('Contacts')));

        objAgency.offices = objOffices;
        objAgency.offices._latestValue[0].contacts = objContacts;


        agency = ko.observableArray([ko.mapping.fromJS(objAgency)]);
        ko.applyBindings(agency);

        initialized = true;

    }
    else {
        agency = ko.observableArray([]);
    }


    var save = function (agency, myStoredValue) {
        // Clear Cache because user submitted the form. We don't have to hold onto data anymore.
        //amplify.store("Agency", null);
        return dataContext.saveChanges(agency);
    };

    var vm = { // This is my view model, my functions are bound to it. 
        //These are wired up to my agency view
        activate: activate,
        agency: agency,
        title: 'agency',
        refresh: refresh, // call refresh function which calls get Agencies
        save: save,
        cacheForm: cacheForm
    };
    return vm;

    function activate() {

        vm.agency;

        if (initialized) {
            return;
        }

        initialized = false;

        return refresh();

    }

    function refresh() {
        return dataContext.getAgency(agency);
    }


    function cacheForm(agency) {
        // GET my object from agency vm
        var agency = ko.toJS(agency);

        var s = YUI().use("json-stringify", function (Y) {

            var jsonStrAgency = Y.JSON.stringify(agency, ["activities", "agencyName", "agencyID", "campaignBillings", "category", "declaredBillings", "immediateParent", "numberOfEmployees", "ultimateParent", "uRL"]); // Use an array of acceptable object key names as a whitelist.
            var jsonStrOffices, jsonStrContacts;

            for (i in agency.offices) {
                jsonStrOffices = Y.JSON.stringify(agency.offices, ["address1", "address2", "address3", "address4", "address5", "agencyID", "faxNumber", "officeID", "postCode", "telephoneNumber"]);

                for (ii in agency.offices[i].contacts) {
                    jsonStrContacts = Y.JSON.stringify(agency.offices[i].contacts, ["agencyID", "emailAddress", "firstName", "jobName", "officeID", "personID", "surName", "title"]);
                }
            }

            localStorage.setItem('Agency', jsonStrAgency);
            localStorage.setItem('Offices', jsonStrOffices);
            localStorage.setItem('Contacts', jsonStrContacts);
        });
    }
});

Node child = rows.getChild(0);
rows.removeChild(child);

Node child = rows.getChild(1);
rows.removeChild(child);

Node child = rows.getChild(2); // Exception!

 while (rows.hasChildNode()) {
   rows.removeChild(rows.getFirstChild());
 }

for (int i = count; i >= 0; i--) {
  rows.removeChild(rows.getChild(i));
}

rows.setInnerHTML("");

rows.removeAllChildren();

class Event
  has_many :votes
  has_many :user_votes,
             ->() { where({user_id: Thread.current[:user]&.id}.compact) },
             class_name: 'Vote'

  def self.using_user(user)
    old_user, Thread.current[:user] = Thread.current[:user], user
    yeild
  ensure
    Thread.current[:user] = old_user
  end
end

Event.using_user(current_user) do
  Event.includes(:user_votes).where("votes.id IS NULL")
end

Event.
  joins(
   "LEFT OUTER JOIN votes ON votes.event_id = events.id AND " +
   "votes.user_id = #{user.id}"
  ).
  where("votes.id IS NULL")

let arr = [ { "id": 1, "name": "group1", "users": [ { "id": 1, "name": "Mike" }, { "id": 2, "name": "Steve" }, { "id": 3, "name": "John" } ] }, { "id": 2, "name": "group2", "users": [ { "id": 4, "name": "Phill" }, { "id": 5, "name": "Joe" }, { "id": 6, "name": "Dominik" } ] } ];

function filterUsers(arr, name) {
  return arr.map(obj => {
    return {
      ...obj,
      "users": obj.users.filter(user => user.name === name)
    };
  });
}

console.log(filterUsers(arr, "Mike"));