def html_escape(s, quote=True):
    """
    Replace special characters "&", "<" and ">" to HTML-safe sequences.
    If the optional flag quote is true (the default), the quotation mark
    characters, both double quote (") and single quote (') characters are also
    translated.

    This code was taken verbatim from the Python 3.5.2 standard library, module
    `html`, function `escape`, and is only renamed `html_escape` here.
    """
    s = s.replace('&', '&amp;')
    s = s.replace('<', '&lt;')
    s = s.replace('>', '&gt;')
    if quote:
        s = s.replace('"', '&quot;')
        s = s.replace("'", '&#x27;')
    return s
