In TCL How to skip command if it dosen't have any entity to select.

Hello everyone,

I have created a sample script attached below. I want a modification in it. For example if I want to move knuckle solid in knuckle comps, but If I didn't receive the knuckle geometry from my client and I run the script. If this solid is not there to select then this command file stops and execute an error. So I want to skip the particular commands if there is no solid for selection.

*createentity comps includeid=0 name="KNUCKLE"
*createmarkpanel solids 1 "Select Knuckle Geometry";
*movemark solids 1 "KNUCKLE"
*createmark components 3 "KNUCKLE"
*createstringarray 2 "elements_off" "geometry_on"
*hideentitybymark 3 1 2
*clearmark solids 1
*createentity comps includeid=0 name="DISC"

so in the createmarkpanel if I didn't have any geometry to select .... and without selecting any geometry if I proceed it should skip the commands till createenity comps includeid=0

So if solution available please guide

Thanks & Regards,

Shubham Dhokare