locale: various improvements (#3860)

- fix delocalize return type
- fix arg names
- add missing args

stdlib/2and3/locale.pyi

@@ -1,7 +1,7 @@
 # Stubs for locale
 
 from decimal import Decimal
-from typing import Any, Dict, Iterable, List, Mapping, Optional, Sequence, Tuple, Union
+from typing import Any, Callable, Dict, Iterable, List, Mapping, Optional, Sequence, Tuple, Union
 import sys
 
 # workaround for mypy#2010
@@ -92,21 +92,21 @@ def normalize(localename: _str) -> _str: ...
 def resetlocale(category: int = ...) -> None: ...
 def strcoll(string1: _str, string2: _str) -> int: ...
 def strxfrm(string: _str) -> _str: ...
-def format(format: _str, val: Union[float, Decimal], grouping: bool = ...,
-           monetary: bool = ...) -> _str: ...
+def format(percent: _str, value: Union[float, Decimal], grouping: bool = ...,
+           monetary: bool = ..., *additional: Any) -> _str: ...
 if sys.version_info >= (3, 7):
-    def format_string(format: _str, val: Any,
+    def format_string(f: _str, val: Any,
                       grouping: bool = ..., monetary: bool = ...) -> _str: ...
 else:
-    def format_string(format: _str, val: Any,
+    def format_string(f: _str, val: Any,
                       grouping: bool = ...) -> _str: ...
 def currency(val: Union[int, float, Decimal], symbol: bool = ..., grouping: bool = ...,
              international: bool = ...) -> _str: ...
 if sys.version_info >= (3, 5):
-    def delocalize(string: _str) -> None: ...
-def atof(string: _str) -> float: ...
+    def delocalize(string: _str) -> _str: ...
+def atof(string: _str, func: Callable[[_str], float] = ...) -> float: ...
 def atoi(string: _str) -> int: ...
-def str(float: float) -> _str: ...
+def str(val: float) -> _str: ...
 
 locale_alias: Dict[_str, _str]  # undocumented
 locale_encoding_alias: Dict[_str, _str]  # undocumented