title: ElasticSearch Python Client: how to get an index name behind an alias
body: <p>I know how to get an alias if any given an index name in ElasticSearch:</p>
  
  <pre><code>es.indices.get_alias(indexname)
  </code></pre>
  
  <p>Is there a way to go the other way around? Something like es.indices.get_index(aliasname)? I implemented a workaround using the es.indices.get_alias for now but I am just curious. </p>