void LoadXml(XElement elt, VisualElementAsset parent, VisualTreeAsset vta)
        {
            VisualElementAsset vea = ResolveType(elt, vta);

            if (vea == null)
            {
                return;
            }

            var parentId = (parent == null ? 0 : parent.id);

            // id includes the parent id, meaning it's dependent on the whole direct hierarchy
            int id = (parentId << 1) ^ vea.GetHashCode();

            vea.parentId = parentId;
            vea.id       = id;

            bool startedRule = ParseAttributes(elt, vea, vta, parent);

            // each vea will creates 0 or 1 style rule, with one or more properties
            // they don't have selectors and are directly referenced by index
            // it's then applied during tree cloning
            vea.ruleIndex = startedRule ? m_Builder.EndRule() : -1;
            if (vea is TemplateAsset)
            {
                vta.templateAssets.Add((TemplateAsset)vea);
            }
            else
            {
                vta.visualElementAssets.Add(vea);
            }

            if (elt.HasElements)
            {
                foreach (XElement child in elt.Elements())
                {
                    if (child.Name.LocalName == k_StyleReferenceNode)
                    {
                        LoadStyleReferenceNode(vea, child);
                    }
                    else
                    {
                        LoadXml(child, vea, vta);
                    }
                }
            }
        }