Render tree using ISSN.

def show_periodical_tree_by_issn(issn):
    """
    Render tree using ISSN.
    """
    trees = tree_handler().trees_by_issn(issn)

    if not trees:
        abort(404, "Dokument s ISSN '%s' není dostupný." % issn)

    return render_trees(
        trees,
        partial(web_tools.compose_tree_path, issn=True)
    )