def hello(name: str) -> str:
    """
    This is module function and it is added to documentation even if it does
    not have a docstring. Function signature will be also generated respecting
    regular and comment-style type annotations. Let's use PEP 257 format here.

    Examples::

        # Google-style code block here, but we could use Markdown code block as well
        >>> hello('John')
        'Hello, John!'

        >>> hello('')
        'Hello!'

    Arguments:
        name -- Name of the person to greet.

    Returns:
        A greeting. No need to put types here if you use type annotations.
    """
    if not name:
        return "Hello!"

    return f"Hello, {name}!"