code: def list_clusters(self):
          
          resp = self.instance_admin_client.list_clusters(
              self.instance_admin_client.instance_path(self.project, "-")
          )
          clusters = []
          instances = {}
          for cluster in resp.clusters:
              match_cluster_name = _CLUSTER_NAME_RE.match(cluster.name)
              instance_id = match_cluster_name.group("instance")
              if instance_id not in instances:
                  instances[instance_id] = self.instance(instance_id)
              clusters.append(Cluster.from_pb(cluster, instances[instance_id]))
          return clusters, resp.failed_locations
docs: List the clusters in the project.
  
          For example:
  
          .. literalinclude:: snippets.py
              :start-after: [START bigtable_list_clusters_in_project]
              :end-before: [END bigtable_list_clusters_in_project]
  
          :rtype: tuple
          :returns:
              (clusters, failed_locations), where 'clusters' is list of
              :class:`google.cloud.bigtable.instance.Cluster`, and
              'failed_locations' is a list of strings representing
              locations which could not be resolved.