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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def parse_toc(html_content):
 """ Parse TOC of HTML content if the SHOW_TOC config is true. :param html_content: raw HTML content :return: tuple(processed HTML, toc list, toc HTML unordered list) """

    from flask import current_app
    from veripress.model.toc import HtmlTocParser

    if current_app.config['SHOW_TOC']:
        toc_parser = HtmlTocParser()
        toc_parser.feed(html_content)
        toc_html = toc_parser.toc_html(
            depth=current_app.config['TOC_DEPTH'],
            lowest_level=current_app.config['TOC_LOWEST_LEVEL'])
        toc = toc_parser.toc(
            depth=current_app.config['TOC_DEPTH'],
            lowest_level=current_app.config['TOC_LOWEST_LEVEL'])
        return toc_parser.html, toc, toc_html
    else:
        return html_content, None, None