docs: def load(cls, context_id, persistence_engine=None):
          """Load and instantiate a Context from the persistence_engine."""
          if not persistence_engine:
              from furious.config import get_default_persistence_engine
              persistence_engine = get_default_persistence_engine()
  
          if not persistence_engine:
              raise RuntimeError(
                  'Specify a valid persistence_engine to load the context.')
  
          return persistence_engine.load_context(context_id)