As specified in
http://plantuml.com/preprocessing I can define:
!definelong a(agr1="TBD1",arg2="TBD2")
...
!enddefinelong
Now, I want to call a, but omit arg1:
a(,"val2")
I want a to use the default "TBD1" value for arg1 and val2 for arg2
Is it possible?