No need for this. If we modify the method get_identifier for:

```
def self.identifier(params)
  @identifier ||= begin
    case params[:type]
      when PNO_TYPE
        params[:pno]
      when TNO_TYPE
        params[:tno]
       else
         .....
       end
     end
  end
 end
```
Use it everywhere needed with `identifier(params)`