What does this Python code print? (chainmap-lookup)

Question

from collections import ChainMap
defaults = {"host": "localhost", "port": 80}
user = {"port": 8080}
cfg = ChainMap(user, defaults)
print(cfg["host"], cfg["port"])

Accepted Answer

localhost 8080

`ChainMap(*maps)` groups multiple dicts into a single view: lookup walks the maps in the order given and returns the first hit. `cfg["port"]` finds 8080 in `user` and stops. `cfg["host"]` misses `user`, falls through to `defaults`, and returns 'localhost'. Writes go to the FIRST map only — so `cfg["debug"] = True` mutates `user`, leaving `defaults` untouched. See collections.ChainMap docs — perfect for CLI-args-over-env-over-defaults config layering.

What does this print?