code: def getAuthenticatedRole(store):
      
      def tx():
          def addToEveryone(newAuthenticatedRole):
              newAuthenticatedRole.becomeMemberOf(getEveryoneRole(store))
              return newAuthenticatedRole
          return store.findOrCreate(Role, addToEveryone, externalID=u'Authenticated')
      return store.transact(tx)
docs: Get the base 'Authenticated' role for this store, which is the role that is
      given to every user who is explicitly identified by a non-anonymous
      username.