[ Closed ] holes of a function

i want to know if the Graph is able to show the undefined value of y, a hole represented by a circle, as i entered a rational function y= x/(x-1). When i enter the x=1, there were no y value found which is reasonable, but the function showed in the graph looks as a smooth line. So i wonder if there is a edit or some button to use to make the hole as a circle on the graph that makes the hole stands out better?