A curious key represent and a little prob
For scalar aggregations, you can:

```
max_id, min_id = User.select(fn.MAX(User.id), fn.MIN(User.id)).scalar(as_tuple=True)
```

If you want "User" instances, then assign an alias to disambiguate the selected columns:

```
query = User.select(fn.MAX(User.id).alias('max_id'), fn.MIN(User.id).alias('min_id'))
user_obj = query[0]
print(user_obj.max_id, user_obj.min_id)
```
```python
In [1]: from apps.models.offline.user import *

In [2]: from peewee import *

In [16]: User.select(fn.MAX(User.id), fn.MIN(User.id)).sql()
Out[16]: ('SELECT MAX(`t1`.`id`), MIN(`t1`.`id`) FROM `user` AS `t1`', [])

In [17]: User.select(fn.MAX(User.id), fn.MIN(User.id)).__dict__
Out[17]:
{'_alias': None,
 '_constructor': None,
 '_cte_list': None,
 '_cursor_wrapper': None,
 '_database': <db.init_db.MyRetryDB at 0x5164810>,
 '_distinct': None,
 '_for_update': None,
 '_from_list': [<Model: User>],
 '_group_by': None,
 '_hash': 7290913799531828381,
 '_having': None,
 '_is_default': False,
 '_join_ctx': <Model: User>,
 '_joins': {},
 '_limit': None,
 '_offset': None,
 '_order_by': None,
 '_returning': [<peewee.Function at 0x540c450>,
  <peewee.Function at 0x540c410>],
 '_row_type': None,
 '_simple_distinct': None,
 '_where': None,
 '_windows': None,
 'model': <Model: User>}

In [18]: User.select(fn.MAX(User.id), fn.MIN(User.id))[0].__dict__
Out[18]: {'__data__': {}, '__rel__': {}, '_dirty': set(), '`id`)': 2493977}

In [19]: User.select(fn.MAX(User.id), fn.MIN(User.id))[0]
Out[19]: <User: None>

In [20]: User.select(fn.MAX(User.id), fn.MIN(User.id))[0].__dict__
Out[20]: {'__data__': {}, '__rel__': {}, '_dirty': set(), '`id`)': 2493979}

In [21]: User.select(fn.MAX(User.id), fn.MIN(User.id))[0].__dict__['`id`)']
Out[21]: 2493982

In [22]: User.select(fn.MIN(User.id), fn.MAX(User.id))[0].__dict__
Out[22]: {'__data__': {}, '__rel__': {}, '_dirty': set(), '`id`)': 1}


In [24]: User.select(fn.MIN(User.id), fn.MAX(User.uid))[0].__dict__
Out[24]:
{'__data__': {},
 '__rel__': {},
 '_dirty': set(),
 '`id`)': 1,
 '`uid`)': u'fffff9fa480038b7e589b7890418b1e3'}
```

Hi:
I have two problem with these code.
First one When I use `User.select(fn.MAX(User.id), fn.MIN(User.id))[0]` why I just get one value `fn.MAX(User.id)` but can not get the `MIN(User.id)` value?

Second one.... when I use .__dict__ to find out why. I have in confused with key `\`id`)\` . Is this deliberate？
Anyone can help me to resolve these problem?
