Human: How many stages are there in the Tour de France? Assistant: 
There are 21 stages in the Tour de France. The first stage is a prologue, which is a short time trial. The second stage is a flat stage, and the third stage is a mountain stage. The fourth stage is a time trial, and the fifth stage is a mountain stage. The sixth stage is a flat stage, and the seventh stage is a mountain stage. The eighth stage is a time trial, and the ninth stage is a mountain stage. The tenth stage is a flat stage, and the eleventh stage is a mountain stage. The twelfth stage is a time trial, and the thirteenth stage is a mountain stage