code: def ListClientsForKeywords(self, keywords, start_time=None, cursor=None):
      
      keywords = set(keywords)
      hash_to_kw = {mysql_utils.Hash(kw): kw for kw in keywords}
      result = {kw: [] for kw in keywords}
  
      query = """
        SELECT keyword_hash, client_id
        FROM client_keywords
        FORCE INDEX (client_index_by_keyword_hash)
        WHERE keyword_hash IN ({})
      """.format(", ".join(["%s"] * len(result)))
      args = list(iterkeys(hash_to_kw))
      if start_time:
        query += " AND timestamp >= FROM_UNIXTIME(%s)"
        args.append(mysql_utils.RDFDatetimeToTimestamp(start_time))
      cursor.execute(query, args)
  
      for kw_hash, cid in cursor.fetchall():
        result[hash_to_kw[kw_hash]].append(db_utils.IntToClientID(cid))
      return result
docs: Lists the clients associated with keywords.