using another style for optional arg

stubs/pydu/cmd.pyi

@@ -1,22 +1,22 @@
 """Stubs for cmd"""
-from typing import Optional, Tuple, List, Union
+from typing import Tuple, List, Union
 
 
 class TimeoutExpired(Exception):
 
     def __init__(self, cmd: str,
                  timeout: Union[int, float],
-                 output: Optional[str]=...,
-                 stderr: Optional[str]=...) -> None: ...
+                 output: dict=None,
+                 stderr: dict=None) -> None: ...
 
 def run(cmd: str,
         shell: bool=...,
-        env: Optional[dict]=...,
+        env: dict=None,
         timeout: Union[int, float]=...,
         timeinterval: Union[int, float]=...) -> Tuple[int, str]: ...
 def run_with_en_env(cmd: str,
                     shell: bool=...,
-                    env: Optional[dict]=...,
+                    env: dict=None,
                     timeout: Union[int, float]=...,
                     timeinterval: Union[int, float]=...) -> Tuple[int, str]: ...
 def terminate(pid: int) -> None: ...

stubs/pydu/dict.pyi

@@ -1,8 +1,8 @@
 import collections
-from typing import Iterable, Tuple, Any, Optional
+from typing import Iterable, Tuple, Any
 
 
 class CaseInsensitiveDict(collections.MutableMapping):
     _store = ... # type: dict
-    def __init__(self, data: Optional[dict], **kwargs) -> None: ...
+    def __init__(self, data: dict=None, **kwargs) -> None: ...
     def lower_items(self) -> Iterable[Tuple[str, Any]]: ...

stubs/pydu/list.pyi

@@ -1,7 +1,7 @@
-from typing import Optional, Callable, Any, Hashable, Iterable
+from typing import Callable, Any, Hashable, Iterable
 
 
 KeyFunc = Callable[[Any], Hashable]
-def uniq(seq: Iterable[Any], key: Optional[KeyFunc]) -> list: ...
+def uniq(seq: Iterable[Any], key: KeyFunc=None) -> list: ...
 def tolist(obj: Any) -> list: ...
 def flatten(seq: Iterable[Any]) -> Iterable[Any]: ...