Python错误代码：IndexError：索引错误列表索引超出范围

I'm trying to write a function in Python that simulates a horse race. While there's no winner, it clears the screen, shows the list of horses (all have index starting at zero). Then, on the line I've marked, the code messes up. I get the index error list out of range. I'm trying to randomly pick a horse (randomly pick an index number) and add 1 to the value. But I can't seem to figure it out!!I'm trying to write a function in Python that s