code: void popOutputVar() {
      outputVars.pop();
      OutputVar outputVar = outputVars.peek(); // null if outputVars is now empty
      if (outputVar != null) {
        currOutputVarName = outputVar.name();
        currOutputVarIsInited = outputVar.isInited();
      } else {
        currOutputVarName = null;
        currOutputVarIsInited = false;
      }
    }
docs: Pops off the current output variable. The previous output variable again becomes the current.