list_clusters
list_clusters(region, next_token, cluster_status)
Retrieve the list of existing clusters.
Parameters:
- region
- 
              Lists clusters deployed to a given AWS Region. 
- next_token
- 
            The token for the next set of results. 
- cluster_status
- 
            Filters by cluster status. The default is to list all clusters. Valid values: CREATE_IN_PROGRESS|CREATE_FAILED|CREATE_COMPLETE|DELETE_IN_PROGRESS|DELETE_FAILED|UPDATE_IN_PROGRESS|UPDATE_COMPLETE|UPDATE_FAILED