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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 _authenticate(self):
 """ The Namecheap API is a little difficult to work with. Originally this method called PyNamecheap's `domains_getList`, which is connected to an API endpoint that only lists domains registered under the authenticating account. However, an authenticating Namecheap user may be permissioned to manage the DNS of additional domains. Namecheap's API does not offer a way to list these domains. This approach to detecting permissioned relies on some implementation details of the Namecheap API and the PyNamecheap module: * If the user does not own the domain, or is not permissioned to manage it in any way, Namecheap will return an error status, which PyNamecheap will instantly catch and raise. * If a non-error repsonse is returned, the XML payload is analyzed. If the user owns the domain it immediately returns valid. Otherwise we look for "All" Modification rights, or the hosts-edit permission. This is not feature complete and most-likely misses multiple scenarios where: * a user is privileged to manage the domain DNS, but via another "right" * a user is privileged to manage the domain, but DNS is not configured Important Note: * the Namecheap API has inconsistent use of capitalization with strings and a case-insensitive match should be made. e.g. the following appear in a payload: `False` and 'false', 'OK' and 'Ok'. TODO: * check payload for PremiumDNS <PremiumDnsSubscription> <IsActive>false</IsActive> </PremiumDnsSubscription> * check payload for other types of DNS <DnsDetails ProviderType="FREE" IsUsingOurDNS="true" HostCount="5" EmailType="No Email Service" DynamicDNSStatus="false" IsFailover="false"> <Nameserver>dns1.registrar-servers.com</Nameserver> <Nameserver>dns2.registrar-servers.com</Nameserver> </DnsDetails> """

        extra_payload = {'DomainName': self.domain, }

        try:
            xml = self.client._call('namecheap.domains.getInfo', extra_payload)  # pylint: disable=protected-access
        except namecheap.ApiError as err:
            # this will happen if there is an API connection error
            # OR if the user is not permissioned to manage this domain
            # OR the API request came from a not whitelisted IP
            # we should print the error, so people know how to correct it.
            raise Exception('Authentication failed: `%s`' % str(err))

        xpath = './/{%(ns)s}CommandResponse/{%(ns)s}DomainGetInfoResult' % {
            'ns': namecheap.NAMESPACE}
        domain_info = xml.find(xpath)

        def _check_hosts_permission():
            # this shouldn't happen
            if domain_info is None:
                return False

            # do they own the domain?
            if domain_info.attrib['IsOwner'].lower() == 'true':
                return True

            # look for rights
            xpath_alt = ('.//{%(ns)s}CommandResponse/{%(ns)s}DomainGetInfoResult'
                         '/{%(ns)s}Modificationrights' % {'ns': namecheap.NAMESPACE})
            rights_info = xml.find(xpath_alt)
            if rights_info is None:
                return False

            # all rights
            if rights_info.attrib['All'].lower() == 'true':
                return True

            for right in rights_info.getchildren():
                if right.attrib['Type'].lower() == 'hosts':
                    # we're only looking at hosts, so we can exit now
                    return right.text.lower() == 'ok'

            return None

        permissioned = _check_hosts_permission()
        if not permissioned:
            raise Exception('The domain {} is not controlled by this Namecheap '
                            'account'.format(self.domain))

        # FIXME What is this for?
        self.domain_id = self.domain