public async Task <FunctionIndexTransactionHandler <TFunctionMessage> > CreateFunctionHandlerAsync <TFunctionMessage, TSearchDocument>(
string indexName, Func <FunctionCall <TFunctionMessage>, TSearchDocument> mappingFunc)
where TFunctionMessage : FunctionMessage, new()
where TSearchDocument : class, IHasId, new()
{
var functionIndexer = await _elasticSearchService.CreateFunctionIndexer <TFunctionMessage, TSearchDocument>(indexName, mappingFunc);
var functionHandler = new FunctionIndexTransactionHandler <TFunctionMessage>(functionIndexer);
return(functionHandler);
}