Not paint in a position

If you want to leave a bar space without painting you can use the na constant.

study("My Script")
x=n%10   // n is the bars counter of the system
r=x==7?na:x   // if the value=7 then it not paints

This is a counter of bars modulated in 10 (it generates 0-9 values continuosly)
It will paint columns with numbers 0-9 (except the position 7).