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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 zone(self, name, dns_name=None, description=None):
 """Construct a zone bound to this client. :type name: str :param name: Name of the zone. :type dns_name: str :param dns_name: (Optional) DNS name of the zone. If not passed, then calls to :meth:`zone.create` will fail. :type description: str :param description: (Optional) the description for the zone. If not passed, defaults to the value of 'dns_name'. :rtype: :class:`google.cloud.dns.zone.ManagedZone` :returns: a new ``ManagedZone`` instance. """

        return ManagedZone(name, dns_name, client=self, description=description)