diff --git a/apiserver/apierrors/autogen/generator.py b/apiserver/apierrors/autogen/generator.py
index e5468e0..90100d2 100644
--- a/apiserver/apierrors/autogen/generator.py
+++ b/apiserver/apierrors/autogen/generator.py
@@ -8,9 +8,12 @@ from pathlib import Path
 
 env = jinja2.Environment(
     loader=jinja2.FileSystemLoader(str(Path(__file__).parent)),
-    autoescape=jinja2.select_autoescape(disabled_extensions=('py',), default_for_string=False),
+    autoescape=jinja2.select_autoescape(
+        disabled_extensions=("py",), default_for_string=False
+    ),
     trim_blocks=True,
-    lstrip_blocks=True)
+    lstrip_blocks=True,
+)
 
 
 def env_filter(name=None):
@@ -19,14 +22,14 @@ def env_filter(name=None):
 
 @env_filter()
 def cls_name(name):
-    delims = list(map(re.escape, (' ', '_')))
-    parts = re.split('|'.join(delims), name)
-    return ''.join(x.capitalize() for x in parts)
+    delims = list(map(re.escape, (" ", "_")))
+    parts = re.split("|".join(delims), name)
+    return "".join(x.capitalize() for x in parts)
 
 
 class Generator(object):
-    _base_class_name = 'BaseError'
-    _base_class_module = 'apiserver.apierrors.base'
+    _base_class_name = "BaseError"
+    _base_class_module = "apiserver.apierrors.base"
 
     def __init__(self, path, format_pep8=True, use_md5=True):
         self._use_md5 = use_md5
@@ -35,29 +38,37 @@ class Generator(object):
         self._path.mkdir(parents=True, exist_ok=True)
 
     def _make_init_file(self, path):
-        (self._path / path / '__init__.py').write_bytes('')
+        (self._path / path / "__init__.py").write_bytes("")
 
     def _do_render(self, file, template, context):
-        with file.open('w') as f:
+        with file.open("w") as f:
             result = template.render(
                 base_class_name=self._base_class_name,
                 base_class_module=self._base_class_module,
-                **context)
+                **context
+            )
             if self._format_pep8:
-                result = autopep8.fix_code(result, options={'aggressive': 1, 'verbose': 0, 'max_line_length': 120})
+                import autopep8
+
+                result = autopep8.fix_code(
+                    result,
+                    options={"aggressive": 1, "verbose": 0, "max_line_length": 120},
+                )
             f.write(result)
 
     def _make_section(self, name, code, subcodes):
         self._do_render(
-            file=(self._path / name).with_suffix('.py'),
-            template=env.get_template('templates/section.jinja2'),
-            context=dict(code=code, subcodes=list(subcodes.items()),))
+            file=(self._path / name).with_suffix(".py"),
+            template=env.get_template("templates/section.jinja2"),
+            context=dict(code=code, subcodes=list(subcodes.items()),),
+        )
 
     def _make_init(self, sections):
         self._do_render(
-            file=(self._path / '__init__.py'),
-            template=env.get_template('templates/init.jinja2'),
-            context=dict(sections=sections,))
+            file=(self._path / "__init__.py"),
+            template=env.get_template("templates/init.jinja2"),
+            context=dict(sections=sections,),
+        )
 
     def _key_to_str(self, data):
         if isinstance(data, dict):
@@ -66,11 +77,11 @@ class Generator(object):
 
     def _calc_digest(self, data):
         data = json.dumps(self._key_to_str(data), sort_keys=True)
-        return hashlib.md5(data.encode('utf8')).hexdigest()
+        return hashlib.md5(data.encode("utf8")).hexdigest()
 
     def make_errors(self, errors):
         digest = None
-        digest_file = self._path / 'digest.md5'
+        digest_file = self._path / "digest.md5"
         if self._use_md5:
             digest = self._calc_digest(errors)
             if digest_file.is_file():