#Python 3.7 will give you one less reason to denormalize your code, among other things.

> This change should encourage you in class-design to follow the DRY (don’t repeat yourself) principle and add private methods that reduce duplication of logic across multiple public methods. Prior to 3.7, the performance hit would have been a strong consideration and copying+pasting code was an accepted practice where speed was required.

https://hackernoon.com/5-speed-improvements-in-python-3-7-1b39d1581d86

3.7 is planned for June 2018: https://www.python.org/dev/peps/pep-0537/