<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def execute(self):
 """ Load the cluster and build a GC3Pie configuration snippet. """

        creator = make_creator(self.params.config,
                               storage_path=self.params.storage)
        cluster_name = self.params.cluster
        try:
            cluster = creator.load_cluster(cluster_name)
        except (ClusterNotFound, ConfigurationError) as ex:
            log.error("Listing nodes from cluster %s: %s\n" %
                      (cluster_name, ex))
            return

        from elasticluster.gc3pie_config import create_gc3pie_config_snippet

        if self.params.append:
            path = os.path.expanduser(self.params.append)
            try:
                fd = open(path, 'a')
                fd.write(create_gc3pie_config_snippet(cluster))
                fd.close()
            except IOError as ex:
                log.error("Unable to write configuration to file %s: %s",
                          path, ex)
        else:
            print(create_gc3pie_config_snippet(cluster))