There are only two hard problems in distributed systems:
 2. Exactly-once delivery 
 1. Guaranteed order of messages 
 2. Exactly-once delivery
These are some of my noteworthy answers, in my opinion:
Difference between std::atomic and std::condition_variable wait, notify_* methods
Is `asyncio.sleep(delay)` guarenteed to sleep for at least `delay` seconds?
Weird behaviour of asyncio.CancelledError and "_GatheringFuture exception was never retrieved"
How Method Resolution Order (MRO) is working in this Python code
What is the difference between an object's set of attributes and its namespace?