tl;dr:C clearly stands out as the "single most important and influential programming language." However, as you work with other languages a tension arises - "you’re stuck either writing bad C code or using poorly-suited tools to interface badly with an otherwise good API."
tl;dr:Two types of changes in open source software inflict trauma on communities. A change where everyone has to overhaul their code to get it to work again, or a change to get code idiomatic again. Drew shows examples of both of these in the Python community.
tl;dr:Drew manages releases for free & open-source software, and consistently found ways of making a new mistake each time he shipped a release. Here he shares those mistakes to prevent them from recurring.