Closes#13654
# User-Facing Changes
- Short flags are now fully type-checked,
including null and record signatures for literal arguments:
```nushell
def test [-v: record<l: int>] {};
test -v null # error
test -v {l: ""} # error
def test2 [-v: int] {};
let v = ""
test2 -v $v # error
```
- `polars unpivot` `--index`/`--on` and `into value --columns`
now accept `list` values