Clean Singleton Docstrings

[Random832]

On Sun, Jul 17, 2016, at 03:51, Chris Angelico wrote:
> > True, although the programmer has control over the feature. If you
> > *want* the luxury of exact fractions, you pay the price. If you don't,
> > you make the numbers inexact.
> 
> Not if you have a single "Number" type:

Saying that exact and inexact numbers can't be a single type is like
saying positive and negative numbers can't be the same type.

Saying that fractions and floats can't be a single type is like saying
ASCII strings and UCS-4 strings can't be the same type within the FSR.
"Single abstract Number type" doesn't preclude a "FNR" where some Number
objects are represented as floats and others are not.