Clean Singleton Docstrings

[Chris Angelico]

On Sun, Jul 17, 2016 at 4:04 AM, Random832 <random832 at fastmail.com> wrote:
> On Sat, Jul 16, 2016, at 03:27, Chris Angelico wrote:
>> Will an "Exact" non-integer be stored as Decimal or
>> Fraction? How do you know? They have vastly different semantics, and
>> you should be able to choose.
>
> Er, the point is for them to _not_ have different semantics. A decimal
> storage format would simply be an optimization for a fraction whose
> denominator is a power of 10 (or of 2 and 5)
>
> The semantics of the current Decimal class are those of an inexact
> number.

In that case, an 'Exact' non-integer will have appalling performance -
fractions.Fraction doesn't really work all that nicely when the
numbers start getting huge.

ChrisA