the problem is none of these are 'wrong', in they give an answer depending on some rather cryptic rules and are correct for those rules. ``.loc`` now obeys rational (pardon the pun) rules.

We could always make a float slice never fallback, so (6), (7), (8) would return the same (its the ``s[2.0:5]`` that is weird here I think, wheras ``s[2:5]`` is very ambiguous.

```
In [5]: s[2:5]
Out[5]: 
5.0     2
7.5     3
10.0    4
dtype: int64

In [6]: s[2.0:5.0]
Out[6]: 
2.5    1
5.0    2
dtype: int64

In [7]: s[2.0:5]
Out[7]: 
5.0     2
7.5     3
10.0    4
dtype: int64

In [8]: s[2.1:5]
Out[8]: 
2.5    1
5.0    2
dtype: int64
```