stdlib: Improve many __iter__ and constructor methods (#7112)

stdlib/fractions.pyi

@@ -25,9 +25,9 @@ class Fraction(Rational):
     @overload
     def __new__(cls: type[Self], __value: float | Decimal | str, *, _normalize: bool = ...) -> Self: ...
     @classmethod
-    def from_float(cls, f: float) -> Fraction: ...
+    def from_float(cls: type[Self], f: float) -> Self: ...
     @classmethod
-    def from_decimal(cls, dec: Decimal) -> Fraction: ...
+    def from_decimal(cls: type[Self], dec: Decimal) -> Self: ...
     def limit_denominator(self, max_denominator: int = ...) -> Fraction: ...
     if sys.version_info >= (3, 8):
         def as_integer_ratio(self) -> tuple[int, int]: ...