```python import validators validators.domain('localhost') # -> ValidationFailure validators.domain('localhost.') # -> ValidationFailure ``` refs * https://stackoverflow.com/questions/2532053/validate-a-hostname-string edit: or does 'domain' mean 'fully qualified domain name'? ([fqdn](https://github.com/ypcrts/fqdn/blob/develop/fqdn/__init__.py#L65)) then 'localhost' is invalid