def get_gutenberg_text(book: str) -> str:
    """
    Given a string of a Project Gutenberg book, return only the actual book content.
    """
    in_book = False
    result = []
    for line in book.split('\n'):
        if line.startswith('*** END OF THIS PROJECT GUTENBERG EBOOK'):
            break
        if in_book:
            result.append(line)
        if line.startswith('*** START OF THIS PROJECT GUTENBERG EBOOK'):
            in_book = True
    return '\n'.join(result)