string: various fixes (#3814)

stdlib/3/string.pyi

@@ -14,19 +14,19 @@ punctuation: str
 printable: str
 whitespace: str
 
-def capwords(s: str, sep: str = ...) -> str: ...
+def capwords(s: str, sep: Optional[str] = ...) -> str: ...
 
 class Template:
     template: str
 
     def __init__(self, template: str) -> None: ...
-    def substitute(self, mapping: Mapping[str, object] = ..., **kwds: object) -> str: ...
-    def safe_substitute(self, mapping: Mapping[str, object] = ...,
+    def substitute(self, __mapping: Mapping[str, object] = ..., **kwds: object) -> str: ...
+    def safe_substitute(self, __mapping: Mapping[str, object] = ...,
                         **kwds: object) -> str: ...
 
 # TODO(MichalPokorny): This is probably badly and/or loosely typed.
 class Formatter:
-    def format(self, format_string: str, *args: Any, **kwargs: Any) -> str: ...
+    def format(self, __format_string: str, *args: Any, **kwargs: Any) -> str: ...
     def vformat(self, format_string: str, args: Sequence[Any],
                 kwargs: Mapping[str, Any]) -> str: ...
     def parse(self, format_string: str) -> Iterable[Tuple[str, Optional[str], Optional[str], Optional[str]]]: ...

tests/stubtest_whitelists/py38.txt

@@ -167,9 +167,6 @@ signal.sigwaitinfo
 smtplib.SMTP.sendmail
 sre_constants.RANGE_IGNORE
 statistics.NormalDist.samples
-string.Formatter.format
-string.Template.safe_substitute
-string.Template.substitute
 sys.UnraisableHookArgs
 threading.ExceptHookArgs
 time.CLOCK_PROF

tests/stubtest_whitelists/py3_common.txt

@@ -710,7 +710,6 @@ ssl.SSLSocket.recvfrom_into
 ssl.SSLSocket.sendto
 ssl._ASN1Object.__new__
 statistics.median_grouped
-string.capwords
 subprocess.Popen.send_signal
 subprocess.call
 sunau.Au_write.getmark