[ 2667626 ] Slicing within Python inline code

JSONP:

```
"list"   : [1,2,3,4,5],
"values" : <<${list}[:-2]>>
```

Result:

`Error: 'Could not evaluate the Python builtIn <<${list}[:-2]>>. Reason: list indices must be integers or slices, not str'!`

Expected:

Either slicing is resolved or error message that slicing is not supported.
