Question: How do I make a conditional display when using the plottools package?

Dear Maple users

I am defining various geometrical items in the plottools package and finally plot them using the display command. Let's say I have defined:

Circle1:=circle(...):

Circle2:=circle(...):

Line1:=line(...):

etc.

and finally want to plot them with the display command:

display(Circle1,Circle2,Line1,...)

It works, however sometimes I only want some of these items to be plotted. Certain variables at the beginning of the document do control if those items should be plotted or not. Let's say a variable CircleOrNot can be set to have the values "no" or "yes", and if I set it to "yes", it should plot it and if the value is "no", it should not plot it. I know that I can make a conditional statement in the end when dealing with the display command, but it can be quite a mess (condition after condition ...).

What I would like is making a conditional assignment like the following:

If CircleOrNot="yes" then Circle1:=circle(...) else Circle1:=null end if

or something like that, and afterwards use the full display command including all objects:

display(Circle1,Circle2,Line1,...)

But it does not work. I receive an error. There doesn't seem to be an empty statement, which will just be ignored by the display command. How can I do it? Probably someone has a good way to handle this situation.

Best regards,

Erik