The best illustration of the dangers of mutable data structures I have found to date.
Mutable data structures and algorithms based upon them were necessary when computer memory was far more limited than it is today.*
Why are you still using mutable data structures and algorithms based on hardware that doesn’t exist anymore?
I first saw this in a tweet by the Software Exorcist.
* Granting there are cases, the CERN comes to mind, where the memory requirements for some applications exceed available memory. You aren’t working at the CERN are you?