How do I use type annotation in Python?

How do I use type annotation in Python?

Type annotations in Python allow you to specify the expected data types of variables, function parameters, and return values. For example, you can define a function like this:

def add_numbers(a: int, b: int) -> int:
    return a + b

What are the benefits of using type annotations?

Type annotations help with code readability, enable better tooling support, and can catch type-related errors during development.

Can I use type annotations with lists and dictionaries?

Yes, you can use type annotations with collections. For example:

from typing import List, Dict

def process_items(items: List[str]) -> Dict[str, int]:
    return {item: len(item) for item in items}

Are type annotations mandatory in Python?

No, type annotations are optional in Python. They are mainly used for documentation and type checking purposes.