docs: def google_cloud_datastore_delete_expired_sessions(dormant_for=86400, limit=500):
      """
      Deletes expired sessions
      A session is expired if it expires date is set and has passed or
      if it has not been accessed for a given period of time.
  
      :param dormant_for: seconds since last access to delete sessions, defaults to 24 hours.
      :type dormant_for: int
      :param limit: amount to delete in one call of the method, the maximum and default for this is the NDB fetch limit of 500
      :type limit: int
      """
      from vishnu.backend.client.google_cloud_datastore import TABLE_NAME
      from google.cloud import datastore
      from datetime import datetime
      from datetime import timedelta
  
      now = datetime.utcnow()
      last_accessed = now - timedelta(seconds=dormant_for)
  
      client = datastore.Client()
      accessed_query = client.query(kind=TABLE_NAME)
      accessed_query.add_filter("last_accessed", "<=", last_accessed)
      accessed_results = accessed_query.fetch(limit=limit)
  
      expires_query = client.query(kind=TABLE_NAME)
      expires_query.add_filter("expires", "<=", now)
      expires_results = expires_query.fetch(limit=limit)
  
      keys = list()
      for result in accessed_results:
          keys.append(result.key)
      for result in expires_results:
          if result.key not in keys:
              keys.append(result.key)
  
      client.delete_multi(keys)
  
      return len(keys) < limit