[Gmsh] Creation of Physical Line with for loop

[Pietro Vitali]

Good morning everyone!!
I'm new in using gmsh so first of all I apologise for my question in 
case the answer should be obvious;
I'm trying using a for loop to create one Physical Line but gmsh seems 
not to recognise "+=" symbol.
Is there anyone that can help me please?

I tried to use this code:

Physical Line ("beam")={}
For num In {1:100}
     Physical Line ("beam") += {num}
EndFor


I'd like to obtain: Physical Line ("beam") = {1,2,3,4,5,6,7,8,9,......,100}

Where am I wrong?

Thank you very much,

Pietro.