Phone storage is a dict: each key is a name, and each value is either a file size (MB, a number) or a folder (another dict like this). Write used_space(folder) to add up how many MB the folder uses. An empty folder is 0.
used_space({"a.jpg": 3, "Trip": {"b.jpg": 5, "c.mp4": 40}})→48used_space({})→0def used_space(folder):
total = 0
for item in folder.values():
# your code here: if it's a folder, add what it uses; if it's a file, add its size
pass
return total
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