The client does not have 'close' exported

https://github.com/kragniz/python-etcd3/blob/7e716d8f7be866b11f1337c6c438aafa1cda08c3/etcd3/client.py#L170

when I call the client.close(), it raise:
Etcd3Client has no attribute 'close'

Start at etcd3/client.py around line 170 and inspect how the client API is exposed. Reproduce the reported client.close() call and trace why the attribute is unavailable. Done means the client provides a callable close method without raising the reported AttributeError.

Written by the indexing model from the issue text.