PEP 498: Formatted string literals

[ghost]

https://www.python.org/dev/peps/pep-0498 and https://docs.python.org/3.6/reference/lexical_analysis.html#f-strings

shouldn't conflict with any pre-existing valid code

[naftaliharris]

I would definitely like to do this. But, I plan to do so after some of the earlier features like "nonlocal" or "raise from", in (Python 3.0). Prioritizing features in earlier versions of Python 3 means that this interpreter will run more Python 3.x code sooner.