Clean Singleton Docstrings

[Lawrence D’Oliveiro]

On Saturday, July 16, 2016 at 4:20:13 PM UTC+12, Ethan Furman wrote:
>
> On 07/15/2016 09:04 PM, Rustom Mody wrote:
> 
>> Just that suggesting that python's bool notion is straightforward is an
>> unnecessary lie – especially to newbies.
> 
> Python's boolean concept is as simple as it gets -- what is not
> straightforward about it?

The fact that it led to the aforementioned bug.