def exact(s1, s2):
    """
    normalised s1 must be identical to normalised s2

    :param s1: first string
    :param s2: second string
    :return: True if match, False if not
    """
    # keep a copy of these for the provenance reporting
    os1 = s1
    os2 = s2

    # normalise the strings
    s1 = _normalise(s1)
    s2 = _normalise(s2)

    if s1 == s2:
        return u"'{a}' is an exact match with '{b}'".format(a=os1, b=os2)

    return False