'This check is done due to the existance of RFCs without a *homoclave*
since the current algorithm to calculate it had not been created for
the first RFCs ever in Mexico.'

def _has_homoclave(self, rfc):

    rfc_without_homoclave_re = re.compile((u'^[A-Z&\xd1\xf1]{3,4}%s$' % DATE_RE), re.IGNORECASE)
    return (not rfc_without_homoclave_re.match(rfc))
