'Return config validator'

def validator(self):

    root = validator.factory()
    root.accept(u'boolean')
    advanced = root.accept(u'dict')
    self._validator(advanced)
    advanced.accept(u'number', key=u'min_ratio')
    advanced.accept(u'interval', key=u'finished_for')
    advanced.accept(u'boolean', key=u'transmission_seed_limits')
    advanced.accept(u'boolean', key=u'delete_files')
    advanced.accept(u'regexp', key=u'tracker')
    advanced.accept(u'regexp', key=u'preserve_tracker')
    directories_re = advanced.accept(u'list', key=u'directories')
    directories_re.accept(u'regexp')
    return root
