Challenge 3: pathlib File Check — Possible Solution
====================================================================

from pathlib import Path

settings_dir = Path("settings")
settings_dir.mkdir(exist_ok=True)   # make sure the folder itself exists first

config_path = settings_dir / "config.txt"

if config_path.exists():
    print(config_path.suffix)
else:
    config_path.write_text("default config")
    print("Created config.txt with default contents")

Output (first run, when config.txt doesn't exist yet):
Created config.txt with default contents

Output (second run, now that config.txt exists):
.txt

WHY THIS WORKS AS AN ANSWER
------------------------------
settings_dir / "config.txt" reuses the chapter's own Path / operator
example directly — joining a folder Path with a filename string
produces a new, correctly-formed Path object, without manually
concatenating strings and slashes the way older code might.

settings_dir.mkdir(exist_ok=True) is a necessary addition beyond what
the chapter's own brief pathlib example showed: attempting to write a
file into a folder that doesn't exist yet would fail, so the settings
folder itself is created first. exist_ok=True prevents an error if the
folder already exists from a previous run — it's a real, practical
detail this challenge surfaces beyond the chapter's own minimal
example.

config_path.exists() reuses the chapter's own .exists() check exactly,
used here in the "check-then-act" shape the challenge asks for: if the
file is already there, .suffix (also reused directly from the
chapter) reports its extension; if not, .write_text("default config")
creates it in one call, no open()/write()/close() sequence needed,
exactly the one-call convenience the chapter highlighted pathlib for.