from typing import Optional


def join(*args: Optional[str]) -> str:
    """
    Creates a string of space-separated entries from the given arguments.

    `None`s are automatically skipped.

    Typical use-case is to pass a set of CSS class names to this method to
    retrieve the final value of the `class` attribute of an element.
    """
    return " ".join(s for s in args if s is not None)