docs: def get_valid_managers(cls, location):
  		"""
  		Get the valid RepoManagers for this location.
  		"""
  		def by_priority_attr(c):
  			return getattr(c, 'priority', 0)
  		classes = sorted(
  			iter_subclasses(cls), key=by_priority_attr,
  			reverse=True)
  		all_managers = (c(location) for c in classes)
  		return (mgr for mgr in all_managers if mgr.is_valid())