collections, itertools, functools, datetime, regex, and more
Counter, defaultdict, deque, OrderedDict, and namedtuple — specialized containers from the collections module that solve common problems in one line.
chain(), product(), permutations(), groupby(), and more — powerful tools for working with iterables without writing loops.
lru_cache for memoization, partial for pre-filling arguments, reduce for folding, and singledispatch for function overloading.
Dates, times, timezones, and arithmetic. Parse strings into dates, calculate durations, and format output with strftime.
Pattern matching with regular expressions — search, findall, sub, groups, and building patterns that actually make sense.
Replace magic strings and numbers with named constants. Enum, IntEnum, auto(), and type-safe alternatives to loose values.
Build and query a database without installing anything. SQL basics through Python's built-in sqlite3 module.