returns Markdown text of selected fragment.

    Args:
        endpoint: URL, file, or HTML string
        stype: { 'css' | 'xpath' }
        selector: CSS selector or XPath expression
    Returns:
        Markdown text
    Options:
        clean: cleans fragment (lxml.html.clean defaults)
        raw: returns raw HTML fragment
        verbose: show http status, encoding, headers

def frag2text(endpoint, stype, selector,
              clean=False, raw=False, verbose=False):
    """returns Markdown text of selected fragment.

    Args:
        endpoint: URL, file, or HTML string
        stype: { 'css' | 'xpath' }
        selector: CSS selector or XPath expression
    Returns:
        Markdown text
    Options:
        clean: cleans fragment (lxml.html.clean defaults)
        raw: returns raw HTML fragment
        verbose: show http status, encoding, headers
    """
    try:
        return main(endpoint, stype, selector, clean, raw, verbose)
    except StandardError as err:
        return err