code: def from_panel_agg(
      cls, runset: "Runset", panel: "Panel", metric: str
  ) -> "LineKey":
      key = f"{runset.id}-config:group:{panel.groupby}:null:{metric}"
      return cls(key)
  
file_path: wandb/wandb/apis/reports/_helpers.py
imports: from typing import Optional
  from ..public import PanelMetricsHelper, Run
  from .runset import Runset
  from .util import Attr, Base, Panel, nested_get, nested_set
label_desc: Use image node_id 5 for calling the LineKey obj's underlying member method code with example usage: obj.from_panel_agg(cls, runset, panel, metric) and returns: cls