<hello>world</hello>
<hello>1.5</hello>
<hello>5</hello>
<hello>true</hello>
<hello>5</hello>
<hello>27</hello>
<hello>1 2 3 4</hello>
1
2
3
4
<hello>2 4</hello>
2
4

node=<elem key="<b>hello</b>"></elem>, key=Some(<b>hello</b>)
node=<elem ></elem>, key=None
