remove unused imports

Author: dariko

etcd3/baseclient.py

@@ -7,7 +7,6 @@
 
 import semantic_version as sem
 from six.moves import urllib_parse
-import copy
 
 from .apis import AuthAPI
 from .apis import ClusterAPI
@@ -18,7 +17,6 @@
 from .apis import MaintenanceAPI
 from .apis import WatchAPI
 from .errors import UnsupportedServerVersion
-from .errors import Etcd3Exception
 from .stateful import Lease
 from .stateful import Lock
 from .stateful import Txn
@@ -27,9 +25,7 @@
 from .swaggerdefs import get_spec
 from .utils import Etcd3Warning
 from .utils import log
-from .utils import check_param
 from .utils import EtcdEndpoint
-from .utils import retry_all_hosts
 from .version import __version__