docs: async def self_check(self):
          """
          Checks that the platforms configuration is all right.
          """
  
          platforms = set()
  
          for platform in get_platform_settings():
              try:
                  name = platform['class']
                  cls: Type[Platform] = import_class(name)
              except KeyError:
                  yield HealthCheckFail(
                      '00004',
                      'Missing platform `class` name in configuration.'
                  )
              except (AttributeError, ImportError, ValueError):
                  yield HealthCheckFail(
                      '00003',
                      f'Platform "{name}" cannot be imported.'
                  )
              else:
                  if cls in platforms:
                      yield HealthCheckFail(
                          '00002',
                          f'Platform "{name}" is imported more than once.'
                      )
                  platforms.add(cls)
  
                  # noinspection PyTypeChecker
                  async for check in cls.self_check():
                      yield check