Can you explain what annotations are in the Python programming language and how they are used?

Annotations in Python are a way to add metadata to function parameters and return values. They do not affect the execution of the code but help document data types and can be used by static type checkers like mypy.

Example of annotations:

def greet(name: str) -> str:
    return f"Hello, {name}!"

Here, name: str indicates that the parameter name should be a string, and -> str indicates that the function returns a string. Annotations are accessible via the __annotations__ attribute of the function.