docs: async def health_check(cls) -> Iterator[HealthCheckFail]:
          """
          Perform checks of the state itself. So far:
  
          - For each method of the class, check for the presence of a
            health_check() method. If the method is present then call it. This is
            used to allow the context decorator to make some checks on the
            structure of the class.
          """
  
          for k, v in cls.__dict__.items():
              if hasattr(v, 'health_check') and callable(v.health_check):
                  async for check in v.health_check(cls):
                      yield check