How to iterate a slice of children of a NimNode ?

[PMunch]

Correct, children is an 
[iterator](https://nim-lang.org/docs/macros.html#children.i%2CNimNode) so you 
can't slice it. When you do `for child in body[1 .. ^1]:` you're basically 
taking the sequence of Nim nodes, creating a new sequence of Nim nodes 
containing only the slice, and then calling the `items` iterator on that. Note 
that `children` is exactly the same iterator as `items` for Nim nodes.