Two Hard Things in Computer Science

The original

There are only two hard things in computer science - cache invalidation, and naming things

The variant

There are only two hard things in computer science - cache invalidation, and naming things, and off-by-one errors

The distributed systems variant

There are only two hard things in distributed systems - 
    2. Exactly-once delivery 
    1. Guaranteed order of messages
    2. Exactly-once delivery

Humor thereof

/via CommitStrip