code: def admin_url_params(request, params=None):
      
      params = params or {}
      if popup_status(request):
          params[IS_POPUP_VAR] = '1'
      pick_type = popup_pick_type(request)
      if pick_type:
          params['_pick'] = pick_type
      return params
docs: given a request, looks at GET and POST values to determine which params
      should be added. Is used to keep the context of popup and picker mode.