Produce values lazily and consume them one at a time.

Write functions that accept any number of arguments, and unpack collections into calls.

Pass functions as values: sorted(key=...), map, and filter.

Capture state in a closure and wrap behaviour with a decorator.

Model state and behaviour together with a class.

Extend a base class with inheritance, and build objects from other objects.

Give classes natural behaviour with __eq__/__repr__ and computed @property values.

Build alternative constructors with @classmethod, and know which state every instance shares.

Make your class work with len(), for, in, and with by implementing the dunders they call.

Model data with @dataclass, name fixed choices with Enum, and add type hints.

Handle errors cleanly, raise your own, and define a custom exception.

Read structured data with the with-statement, json, and csv.

Truncate or append on purpose, write real lines, and rename into place so a crash cannot corrupt a file.

Encode and decode deliberately, and read the error that says these bytes were never UTF-8.

Organise code into modules and reach for Python's batteries-included stdlib.

Find, extract, and replace text patterns with regular expressions.

Reach for specialized collections: count with Counter, group with defaultdict, queue with deque.

Parse and format timestamps, subtract them safely, and never mix naive with aware.

Name the loops you keep rewriting, keep them lazy, and never call groupby on unsorted rows.

Read the shape of an HTTP call, then handle the half that actually breaks: the status and the parse.