code: def __init__(self) -> None:
      self.frontends = {}
  
imports: import pytest
  from lightning.app.core.flow import LightningFlow
  from lightning.app.core.work import LightningWork
  from lightning.app.frontend.web import StaticWebFrontend
  from lightning.app.utilities.layout import _collect_layout
label_desc: Use image node_id 1 to create a new _MockApp object  with example: obj = _MockApp()