Better fix for lock metadata handling in write_file

Author: glpatcern

cs3client/file.py

@@ -170,7 +170,8 @@ def touch_file(self, auth_token: tuple, resource: Resource) -> None:
         self._log.debug(f'msg="Invoked TouchFile" trace="{res.status.trace}"')
 
     def write_file(
-            self, auth_token: tuple, resource: Resource, content: Union[str, bytes], size: int, lock_md: tuple = None
+            self, auth_token: tuple, resource: Resource, content: Union[str, bytes], size: int,
+            app_name: str = None, lock_id: str = None
     ) -> None:
         """
         Write a file using the given userid as access token. The entire content is written
@@ -182,16 +183,14 @@ def write_file(
         :param resource: Resource to write content to
         :param content: content to write
         :param size: size of content (optional)
-        :param lock_md: tuple (<app_name>, <lock_id>) (optional)
+        :param app_name: application name (optional)
+        :param lock_id: lock id (optional)
         :return: None (Success)
         :raises: FileLockedException (File is locked),
         :raises: AuthenticationException (Authentication failed)
         :raises: UnknownException (Unknown error)
 
         """
-        app_name = lock_id = ''
-        if lock_md:
-            app_name, lock_id = lock_md
         tstart = time.time()
         # prepare endpoint
         if size == -1: