Is it possible to create an uxml template that can accept child elements like ScrollView?

I often want to create a uxml template for a container and put arbitrary child elements in it.
In other words, I want to create custom template like ScrollView.

The following is an example.

The following is pseudo-code, so it just shows the concept.
Is it possible to include content on the parent element side like this?

-- child template --

Code (Container.uxml):

1.  
2. <VisualElement>
3.     <Label text="header text"/>
4.  
5.     <Slot />   <=== replace by parent (three Label elements will be inserted)
6.  
7.     <Label text="footer text"/>
8. </VisualElement>
9.  

-- parent template--

Code (Root.uxml):

1.  
2. <Template src="Container.uxml" name="Container" />
3. <Instance name="page1" template="Container">
4.     <Label text="awesome contents 1" />
5.     <Label text="awesome contents 2" />
6.     <Label text="awesome contents 3" />
7. </Instance>
8.