using mutable in function defintion as optional paramter

[DeaD_EyE]

Is there a good reason why we should not pass the dictionary we want modified by name?

It's not expected that a function mutates objects from the arguments. But sporadically, it's even done in the standard library. One example is heapq.heapify, which mutates the list.

The example with the dataclass is better because it has isolation. The item dict is attached as an attribute to the dataclass-instance.