pkg/strategoxt/baseline/current/bin/sdf2rtg -i ConcreteSyntax.def -o ConcreteSyntax.rtg
[ core-sdf-grammar2rtg | warning ] Cannot generate a nice name for symbol
[ core-sdf-grammar2rtg | warning ] <<{Exp ","}*-CF>-VAR>
[ core-sdf-grammar2rtg | warning ] Please report this bug at
[ core-sdf-grammar2rtg | warning ] - https://catamaran.labs.cs.uu.nl/jira/browse/STR
[ core-sdf-grammar2rtg | warning ] - or martin@cs.uu.nl
[ core-sdf-grammar2rtg | warning ] Resolution: falling back to the ugly name
          "a_0"