def _parse_title(dom, details):
    """
    Parse title/name of the book.

    Args:
        dom (obj): HTMLElement containing whole HTML page.
        details (obj): HTMLElement containing slice of the page with details.

    Returns:
        str: Book's title.

    Raises:
        AssertionError: If title not found.
    """
    title = details.find("h1")

    # if the header is missing, try to parse title from the <title> tag
    if not title:
        title = dom.find("title")
        assert title, "Can't find <title> tag!"

        return title[0].getContent().split("|")[0].strip()

    return title[0].getContent().strip()