Python

Master Python mocking: patch objects at their import location, not where they're defined, to avoid common unittest.mock pitfalls.

Assert specific mock call arguments while ignoring others using unittest.mock.ANY for flexible test assertions without brittle checks.

Use Python assert statements to apply runtime constraints more succinctly than raising ValueError. Learn the trade-offs and best practices.

Process large CSV files without OOM errors by streaming content line-by-line with HTTPX and concurrent.futures for parallel processing.

Speed up Django bulk operations with ProcessPoolExecutor while preserving signals and hooks that bulk_create/bulk_update bypass.

Download and process S3 CSV files in memory using boto3 and tempfile.NamedTemporaryFile without cluttering disk with temporary files.

Use operator.itemgetter for faster sorting and element access with graceful KeyError handling via methodcaller for safer operations.

Master TypeScript's never type and Python's NoReturn for exhaustiveness checking. Flatten nested conditionals with guard clauses for cleaner code.

Fix Django REST Framework to return JSON error responses for 403, 404, 500 errors using middleware instead of default HTML pages.

Learn how Python generators decouple data production from consumption, enabling cleaner code for streaming, polling, and pipeline patterns.

Understand CPython list memory allocation: how lists store pointer references, grow dynamically, and when pre-allocation with [None]*n helps.

Prevent excessive file downloads in Python by streaming with HTTPX and limiting file size with chunk-based validation and memory-safe processing.

Leverage Python's __post_init__ hook to declaratively transform dataclass fields. Automatically serialize data with clean, maintainable code.

Learn efficient patterns for caching database connection objects in Python without import-time side effects or lru_cache complexity.

Fix Python ModuleNotFoundError by using python -m instead of direct script execution to ensure correct sys.path handling for imports.