I have the below code that I use to toggle a third-party macro from
"installed" to "uninstalled" and vice versa:

If AddIns("Hello World").installed = True Then AddIns("Hello
World").installed = False

The problem is I can not seem to come up with code that I can use to
detect if the addin is available. So if a user does not have this
addin available the code will produce an error. I am looking for
something like below (though I know the code is not right but it
illustrates what I would like to do).

If AddIns("Hello World").available = True Then
If AddIns("Hello World").installed = True Then AddIns("Hello
World").installed = False
end if

Does anyone know how I might be able to do this? Thanks in advance
for any assistance.