code: @Override
  	public LexNameSet defaultSBinaryExp(SBinaryExp exp, FreeVarInfo info) throws AnalysisException
  	{
  		LexNameSet names = exp.getLeft().apply(this, info);
  		names.addAll(exp.getRight().apply(this, info));
  		return names;
  	}
docs: *********************** Defaults **************************