Fix style and add Optional type

Author: Pseudolukian

examples/static-credentials/example.py

@@ -1,5 +1,6 @@
 import ydb
 
+
 def test_driver_works(driver: ydb.Driver):
     """Tests the functionality of the YDB driver.
 
@@ -16,6 +17,7 @@ def test_driver_works(driver: ydb.Driver):
     result = pool.execute_with_retries("SELECT 1 as cnt")
     assert result[0].rows[0].cnt == 1
 
+
 def auth_with_static_credentials(endpoint: str, database: str, user: str, password: str, ca_path: str):
     """Authenticate using static credentials.
 
@@ -32,10 +34,10 @@ def auth_with_static_credentials(endpoint: str, database: str, user: str, passwo
     """
 
     driver_config = ydb.DriverConfig(
-        endpoint = endpoint,
-        database = database,
-        credentials = ydb.StaticCredentials.from_user_password(user, password),
-        root_certificates = ydb.auth_helpers.load_ydb_root_certificate(ca_path)
+        endpoint=endpoint,
+        database=database,
+        credentials=ydb.StaticCredentials.from_user_password(user, password),
+        root_certificates=ydb.load_ydb_root_certificate(ca_path)
     )
 
     with ydb.Driver(driver_config=driver_config) as driver:

ydb/auth_helpers.py

@@ -1,13 +1,14 @@
 # -*- coding: utf-8 -*-
 import os
+from typing import Optional
 
 
 def read_bytes(f):
     with open(f, "rb") as fr:
         return fr.read()
 
 
-def load_ydb_root_certificate(path:str = None):
+def load_ydb_root_certificate(path: Optional[str] = None):
     if path is not None and os.path.exists(path):
         return read_bytes(path)
     return None