Loads healthchecks specified in settings.HEALTHCHECKS as dotted import
        paths to the classes. Defaults are listed in `DEFAULT_HEALTHCHECKS`.

def load_default_healthchecks(self):
        """
        Loads healthchecks specified in settings.HEALTHCHECKS as dotted import
        paths to the classes. Defaults are listed in `DEFAULT_HEALTHCHECKS`.
        """
        default_healthchecks = getattr(settings, 'HEALTHCHECKS', DEFAULT_HEALTHCHECKS)
        for healthcheck in default_healthchecks:
            healthcheck = import_string(healthcheck)
            self.register_healthcheck(healthcheck)