code: def AddClientKeywords(self, client_id, keywords):
      
      if client_id not in self.metadatas:
        raise db.UnknownClientError(client_id)
  
      for kw in keywords:
        self.keywords.setdefault(kw, {})
        self.keywords[kw][client_id] = rdfvalue.RDFDatetime.Now()
docs: Associates the provided keywords with the client.