[_operator] Type add and sub mimicking mul in #15598.

Author: hunterhogan

stdlib/_operator.pyi

@@ -1,5 +1,5 @@
 import sys
-from _typeshed import SupportsGetItem, SupportsMul, SupportsRMul
+from _typeshed import SupportsAdd, SupportsGetItem, SupportsMul, SupportsRAdd, SupportsRMul, SupportsRSub, SupportsSub
 from collections.abc import Callable, Container, Iterable, MutableMapping, MutableSequence, Sequence
 from operator import attrgetter as attrgetter, itemgetter as itemgetter, methodcaller as methodcaller
 from typing import Any, AnyStr, Protocol, SupportsAbs, SupportsIndex, TypeVar, overload, type_check_only
@@ -59,7 +59,10 @@ def truth(a: object, /) -> bool: ...
 def is_(a: object, b: object, /) -> bool: ...
 def is_not(a: object, b: object, /) -> bool: ...
 def abs(a: SupportsAbs[_T], /) -> _T: ...
-def add(a, b, /): ...
+@overload
+def add(a: SupportsAdd[_T_contra, _T_co], b: _T_contra, /) -> _T_co: ...
+@overload
+def add(a: _T_contra, b: SupportsRAdd[_T_contra, _T_co], /) -> _T_co: ...
 def and_(a, b, /): ...
 def floordiv(a, b, /): ...
 def index(a: SupportsIndex, /) -> int: ...
@@ -77,7 +80,10 @@ def or_(a, b, /): ...
 def pos(a: _SupportsPos[_T_co], /) -> _T_co: ...
 def pow(a, b, /): ...
 def rshift(a, b, /): ...
-def sub(a, b, /): ...
+@overload
+def sub(a: SupportsSub[_T_contra, _T_co], b: _T_contra, /) -> _T_co: ...
+@overload
+def sub(a: _T_contra, b: SupportsRSub[_T_contra, _T_co], /) -> _T_co: ...
 def truediv(a, b, /): ...
 def xor(a, b, /): ...
 def concat(a: Sequence[_T], b: Sequence[_T], /) -> Sequence[_T]: ...