Can't do filter using fields between single quotes

to deal with fields names with  period or hyphen must use single quotes like this
```python
JSPath("$..'a-bc'").parse(data)

# but we can't filter like this
JSPath("$.user-list'[@.'city-name'=='Austin'")

# nor 
JSPath('$.user-list'[@."city-name"=="Austin"')
 
```

I guess that field names must be enclosed with ` 
to avoid problems