According to the [Python 2.7.12 documentation](https://docs.python.org/2/tutorial/inputoutput.html#fancier-output-formatting):

> 
> `!s` (apply `str()`) and `!r` (apply `repr()`) can be used to convert
>  the value before it is formatted.
> 
> 
> 
> ```
> >>> import math
> >>> print 'The value of PI is approximately {}.'.format(math.pi)
> The value of PI is approximately 3.14159265359.
> >>> print 'The value of PI is approximately {!r}.'.format(math.pi)
> The value of PI is approximately 3.141592653589793.
> 
> ```
> 
> 

Interestingly, the converted value is the output of `repr()`, rather than `str()`.

```
>>> str(math.pi)
'3.14159265359'
>>> repr(math.pi)
'3.141592653589793'

```

So what does "convert the value" mean here? Making it less human-readable?