Programming Tip #3: Functional Core, Imperative Shell for AWS Lambdas. Make all code pure functions, then put all side effects and exceptions inside your handler only.

Learn more:

• https://destroyallsoftware.com/screencasts/catalog/functional-core-imperative-shell
• https://returns.readthedocs.io/en/latest/pages/io.html
• http://mypy-lang.org
• https://pypi.org/project/PyMonad/