Python’s new template strings ... we don’t need string.templatelib to make template strings. Those we can construct just by using the t-string syntax anywhere in our code.

Python dataclasses ... float shelf_id: int = 0 Once a dataclass is created it is functionally identical to a regular class. There is no performance penalty for using a dataclass.

including inner functions and Python's scoping rules. I do, however, want to ask the question "how can you use Mypy to check all of this?" from typing import Callable def foo(x: int) -> Callable: def ...