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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 update(zone, name, ttl, rdtype, data, nameserver='127.0.0.1', timeout=5,
           replace=False, port=53, **kwargs):
    '''
    Add, replace, or update a DNS record.
    nameserver must be an IP address and the minion running this module
    must have update privileges on that server.
    If replace is true, first deletes all records for this name and type.

    CLI Example:

    .. code-block:: bash

        salt ns1 ddns.update example.com host1 60 A 10.0.0.1
    '''
    name = six.text_type(name)

    if name[-1:] == '.':
        fqdn = name
    else:
        fqdn = '{0}.{1}'.format(name, zone)

    request = dns.message.make_query(fqdn, rdtype)
    answer = dns.query.udp(request, nameserver, timeout, port)

    rdtype = dns.rdatatype.from_text(rdtype)
    rdata = dns.rdata.from_text(dns.rdataclass.IN, rdtype, data)

    keyring = _get_keyring(_config('keyfile', **kwargs))
    keyname = _config('keyname', **kwargs)
    keyalgorithm = _config('keyalgorithm',
                           **kwargs) or 'HMAC-MD5.SIG-ALG.REG.INT'

    is_exist = False
    for rrset in answer.answer:
        if rdata in rrset.items:
            if ttl == rrset.ttl:
                if len(answer.answer) >= 1 or len(rrset.items) >= 1:
                    is_exist = True
                    break

    dns_update = dns.update.Update(zone, keyring=keyring, keyname=keyname,
                                   keyalgorithm=keyalgorithm)
    if replace:
        dns_update.replace(name, ttl, rdata)
    elif not is_exist:
        dns_update.add(name, ttl, rdata)
    else:
        return None
    answer = dns.query.udp(dns_update, nameserver, timeout, port)
    if answer.rcode() > 0:
        return False
    return True