How do I use mypy for type checking in Python?

How do I use mypy for type checking in Python?

You can use mypy by installing it via pip and then running it on your Python files to check for type errors.

Can you show me a simple example of how to annotate types in Python?

Sure! Here's a simple function:

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

This function specifies that both parameters and the return type are integers.

What if I have a function that can accept multiple types?

You can use the Union type from the typing module. For example:

from typing import Union

def process(value: Union[int, str]) -> None:
    print(value)

How do I run mypy on my code?

You can run mypy from the command line by typing mypy your_file.py. It will check for type errors and report them.