def unescape(s):
    """Replace escaped HTML-special characters by their originals."""
    if '&' not in s:
        return s
    s = s.replace('&lt;', '<')
    s = s.replace('&gt;', '>')
    s = s.replace('&apos;', "'")
    s = s.replace('&quot;', '"')
    s = s.replace('&amp;', '&')
    return s
