currently this works correctly:

```
>>> '%8s %8s' % (None, 1)
'    None        1'
```

but conversion to f-string fails:

```
>>> f'{None:>8} {1:>8}'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported format string passed to NoneType.__format__
```

my proposal is to implement alignment `__format__` for `None` following the same as for `str` for alignment specifiers