code: public VarBindingDef bind( VarDef varDef, VarValueDef valueDef)
      {
      if( valueDef != null && !varDef.isApplicable( valueDef))
        {
        throw new IllegalArgumentException( "Value=" + valueDef + " is not defined for var=" + varDef);
        }
      
      varDef_ = varDef;
      valueDef_ = valueDef;
      effCondition_ = null;
  
      return this;
      }
docs: Changes this input variable binding.