Nested Data

Why this matters

Every REST API response is nested JSON, and navigating dicts inside lists inside dicts is a daily task in web and data work. Libraries like requests and pydantic hand back exactly this shape.

Common pitfalls

• Blindly chaining d['a']['b']['c']. If any key is missing, it raises KeyError; use .get() chains or dict.get('a', {}).get('b').
• Copying nested dicts with d.copy(). That is shallow; inner dicts still alias. Use copy.deepcopy() for true clones.
• Assuming JSON keys are always strings. In Python dicts they can be any hashable type, which breaks json.dumps on int keys.