code: public VarSet addMember( IVarDef var)
      {
      assert var != null;
      assert var.getName() != null;
  
      if( findMember( var.getName()) >= 0)
        {
        throw new IllegalStateException( "Member=" + var.getName() + " already defined for varSet=" + getPathName());
        }
  
      members_.add( var);
      var.setParent( this);
      var.setSeqNum( getNextSeqNum());
  
      return this;
      }
docs: Adds an input variable to this set.