There are only two hard things in Computer Science: cache invalidation
and naming things.
                                                         -- Phil Karlton

There are only two hard problems in distributed systems:
2. Exactly-once delivery.
1. Guaranteed order of messages.
2. Exactly-once delivery.
                                                      -- Mathias Verraes

There are two hard things in Computer Science: cache invalidation,
naming things, and off-by-one errors.
      -- Leon Bambrick at https://twitter.com/secretGeek/status/7269997868