diff --git a/dpgen2/entrypoint/main.py b/dpgen2/entrypoint/main.py
index 08493917..00ee55e3 100644
--- a/dpgen2/entrypoint/main.py
+++ b/dpgen2/entrypoint/main.py
@@ -1,22 +1,12 @@
 import argparse
 import json
 import logging
-import os
 import textwrap
 from typing import (
     List,
     Optional,
 )
 
-import dflow
-from dflow import (
-    Step,
-    Steps,
-    Workflow,
-    download_artifact,
-    upload_artifact,
-)
-
 from dpgen2 import (
     __version__,
 )
diff --git a/dpgen2/entrypoint/showkey.py b/dpgen2/entrypoint/showkey.py
index 36055426..498533bf 100644
--- a/dpgen2/entrypoint/showkey.py
+++ b/dpgen2/entrypoint/showkey.py
@@ -1,11 +1,3 @@
-import glob
-import os
-import pickle
-from pathlib import (
-    Path,
-)
-
-import dpdata
 from dflow import (
     Workflow,
 )
diff --git a/dpgen2/entrypoint/status.py b/dpgen2/entrypoint/status.py
index d6164647..1698f518 100644
--- a/dpgen2/entrypoint/status.py
+++ b/dpgen2/entrypoint/status.py
@@ -1,9 +1,7 @@
 import logging
 from typing import (
     Dict,
-    List,
     Optional,
-    Union,
 )
 
 from dflow import (
diff --git a/dpgen2/entrypoint/submit.py b/dpgen2/entrypoint/submit.py
index 203478dc..9e07374f 100644
--- a/dpgen2/entrypoint/submit.py
+++ b/dpgen2/entrypoint/submit.py
@@ -1,10 +1,7 @@
 import copy
-import glob
 import json
 import logging
 import os
-import pickle
-import re
 from copy import (
     deepcopy,
 )
@@ -15,12 +12,8 @@
     Dict,
     List,
     Optional,
-    Tuple,
-    Type,
-    Union,
 )
 
-import dpdata
 from dflow import (
     ArgoStep,
     InputArtifact,
@@ -588,7 +581,7 @@ def workflow_concurrent_learning(
     if fp_style == "deepmd":
         assert (
             "teacher_model_path" in fp_config["run"]
-        ), f"Cannot find 'teacher_model_path' in config['fp']['run_config'] when fp_style == 'deepmd'"
+        ), "Cannot find 'teacher_model_path' in config['fp']['run_config'] when fp_style == 'deepmd'"
         assert os.path.exists(
             fp_config["run"]["teacher_model_path"]
         ), f"No such file: {fp_config['run']['teacher_model_path']}"
diff --git a/dpgen2/entrypoint/watch.py b/dpgen2/entrypoint/watch.py
index 891be817..e8654039 100644
--- a/dpgen2/entrypoint/watch.py
+++ b/dpgen2/entrypoint/watch.py
@@ -4,7 +4,6 @@
     Dict,
     List,
     Optional,
-    Union,
 )
 
 from dflow import (
@@ -43,28 +42,29 @@ def update_finished_steps(
     if finished_keys is not None:
         diff_keys = []
         for kk in wf_keys:
-            if not (kk in finished_keys):
+            if kk not in finished_keys:
                 diff_keys.append(kk)
     else:
         diff_keys = wf_keys
     for kk in diff_keys:
-        logging.info(f'steps {kk.ljust(50,"-")} finished')
+        logging.info(f"steps {kk.ljust(50, '-')} finished")
         if download:
             download_dpgen2_artifacts(wf, kk, prefix=prefix, chk_pnt=chk_pnt)
-            logging.info(f'steps {kk.ljust(50,"-")} downloaded')
+            logging.info(f"steps {kk.ljust(50, '-')} downloaded")
     finished_keys = wf_keys
     return finished_keys
 
 
 def watch(
     workflow_id,
-    wf_config: Optional[Dict] = {},
+    wf_config: Optional[dict] = None,
     watching_keys: Optional[List] = default_watching_keys,
     frequency: float = 600.0,
     download: bool = False,
     prefix: Optional[str] = None,
     chk_pnt: bool = False,
 ):
+    wf_config = wf_config or {}
     wf_config = normalize_args(wf_config)
 
     global_config_workflow(wf_config)
diff --git a/dpgen2/entrypoint/workflow.py b/dpgen2/entrypoint/workflow.py
index 8cc4cc04..6e7e363a 100644
--- a/dpgen2/entrypoint/workflow.py
+++ b/dpgen2/entrypoint/workflow.py
@@ -1,7 +1,4 @@
 import argparse
-import json
-import logging
-import os
 from typing import (
     Optional,
 )
@@ -38,8 +35,9 @@ def add_subparser_workflow_subcommand(subparsers, command: str):
 def execute_workflow_subcommand(
     command: str,
     wfid: str,
-    wf_config: Optional[dict] = {},
+    wf_config: Optional[dict] = None,
 ):
+    wf_config = wf_config or {}
     wf_config = normalize_args(wf_config)
     global_config_workflow(wf_config)
     wf = Workflow(id=wfid)
diff --git a/dpgen2/fp/prep_fp.py b/dpgen2/fp/prep_fp.py
index a43f582a..962be031 100644
--- a/dpgen2/fp/prep_fp.py
+++ b/dpgen2/fp/prep_fp.py
@@ -1,5 +1,3 @@
-import json
-import os
 from abc import (
     ABC,
     abstractmethod,
@@ -9,11 +7,8 @@
 )
 from typing import (
     Any,
-    Dict,
     List,
-    Set,
     Tuple,
-    Union,
 )
 
 import dpdata
diff --git a/dpgen2/fp/run_fp.py b/dpgen2/fp/run_fp.py
index 64e0c3a8..254936d0 100644
--- a/dpgen2/fp/run_fp.py
+++ b/dpgen2/fp/run_fp.py
@@ -1,4 +1,3 @@
-import json
 import os
 from abc import (
     ABC,
@@ -10,12 +9,10 @@
 from typing import (
     Dict,
     List,
-    Set,
     Tuple,
 )
 
 import dargs
-import dpdata
 from dflow.python import (
     OP,
     OPIO,
diff --git a/dpgen2/fp/vasp.py b/dpgen2/fp/vasp.py
index 8d8cebbe..b8b12b28 100644
--- a/dpgen2/fp/vasp.py
+++ b/dpgen2/fp/vasp.py
@@ -6,12 +6,8 @@
     Path,
 )
 from typing import (
-    Dict,
     List,
-    Optional,
-    Set,
     Tuple,
-    Union,
 )
 
 import dpdata
diff --git a/dpgen2/fp/vasp_input.py b/dpgen2/fp/vasp_input.py
index 8bbad820..2b60b18e 100644
--- a/dpgen2/fp/vasp_input.py
+++ b/dpgen2/fp/vasp_input.py
@@ -10,7 +10,6 @@
     Union,
 )
 
-import dpdata
 import numpy as np
 from dargs import (
     Argument,