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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 get_cluster_port_names(self, cluster_name):

 """ return a list of the port names under XIV CLuster """

        port_names = list()
        for host_name in self.get_hosts_by_clusters()[cluster_name]:
            port_names.extend(self.get_hosts_by_name(host_name))
        return port_names