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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _validate(rrset, rrsigset, keys, origin=None, now=None):
 """Validate an RRset @param rrset: The RRset to validate @type rrset: dns.rrset.RRset or (dns.name.Name, dns.rdataset.Rdataset) tuple @param rrsigset: The signature RRset @type rrsigset: dns.rrset.RRset or (dns.name.Name, dns.rdataset.Rdataset) tuple @param keys: The key dictionary. @type keys: a dictionary keyed by dns.name.Name with node or rdataset values @param origin: The origin to use for relative names @type origin: dns.name.Name or None @param now: The time to use when validating the signatures. The default is the current time. @type now: int """


    if isinstance(origin, (str, unicode)):
        origin = dns.name.from_text(origin, dns.name.root)

    if isinstance(rrset, tuple):
        rrname = rrset[0]
    else:
        rrname = rrset.name

    if isinstance(rrsigset, tuple):
        rrsigname = rrsigset[0]
        rrsigrdataset = rrsigset[1]
    else:
        rrsigname = rrsigset.name
        rrsigrdataset = rrsigset

    rrname = rrname.choose_relativity(origin)
    rrsigname = rrname.choose_relativity(origin)
    if rrname != rrsigname:
        raise ValidationFailure, "owner names do not match"

    for rrsig in rrsigrdataset:
        try:
            _validate_rrsig(rrset, rrsig, keys, origin, now)
            return
        except ValidationFailure, e:
            pass
    raise ValidationFailure, "no RRSIGs validated"