'Adds a jail.
Adds a new jail if not already present which should use the
given backend.
Parameters
name : str
The name of the jail.
backend : str
The backend to use.
db : Fail2BanDb
Fail2Ban\'s persistent database instance.
Raises
DuplicateJailException
If jail name is already present.'

def add(self, name, backend, db=None):

    with self.__lock:
        if (name in self._jails):
            if noduplicates:
                raise DuplicateJailException(name)
        else:
            self._jails[name] = Jail(name, backend, db)
