Split stdlib into Python 2 and 3 versions (#5442)

All new files in stdlib/@python2 are straight copies of the
corresponding files in stdlib.

stdlib/@python2/fractions.pyi

@@ -0,0 +1,164 @@
+import sys
+from decimal import Decimal
+from numbers import Integral, Rational, Real
+from typing import Optional, Tuple, Type, TypeVar, Union, overload
+from typing_extensions import Literal
+
+_ComparableNum = Union[int, float, Decimal, Real]
+_T = TypeVar("_T")
+
+if sys.version_info < (3, 9):
+    @overload
+    def gcd(a: int, b: int) -> int: ...
+    @overload
+    def gcd(a: Integral, b: int) -> Integral: ...
+    @overload
+    def gcd(a: int, b: Integral) -> Integral: ...
+    @overload
+    def gcd(a: Integral, b: Integral) -> Integral: ...
+
+class Fraction(Rational):
+    @overload
+    def __new__(
+        cls: Type[_T],
+        numerator: Union[int, Rational] = ...,
+        denominator: Optional[Union[int, Rational]] = ...,
+        *,
+        _normalize: bool = ...,
+    ) -> _T: ...
+    @overload
+    def __new__(cls: Type[_T], __value: Union[float, Decimal, str], *, _normalize: bool = ...) -> _T: ...
+    @classmethod
+    def from_float(cls, f: float) -> Fraction: ...
+    @classmethod
+    def from_decimal(cls, dec: Decimal) -> Fraction: ...
+    def limit_denominator(self, max_denominator: int = ...) -> Fraction: ...
+    if sys.version_info >= (3, 8):
+        def as_integer_ratio(self) -> Tuple[int, int]: ...
+    @property
+    def numerator(self) -> int: ...
+    @property
+    def denominator(self) -> int: ...
+    @overload
+    def __add__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __add__(self, other: float) -> float: ...
+    @overload
+    def __add__(self, other: complex) -> complex: ...
+    @overload
+    def __radd__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __radd__(self, other: float) -> float: ...
+    @overload
+    def __radd__(self, other: complex) -> complex: ...
+    @overload
+    def __sub__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __sub__(self, other: float) -> float: ...
+    @overload
+    def __sub__(self, other: complex) -> complex: ...
+    @overload
+    def __rsub__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __rsub__(self, other: float) -> float: ...
+    @overload
+    def __rsub__(self, other: complex) -> complex: ...
+    @overload
+    def __mul__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __mul__(self, other: float) -> float: ...
+    @overload
+    def __mul__(self, other: complex) -> complex: ...
+    @overload
+    def __rmul__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __rmul__(self, other: float) -> float: ...
+    @overload
+    def __rmul__(self, other: complex) -> complex: ...
+    @overload
+    def __truediv__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __truediv__(self, other: float) -> float: ...
+    @overload
+    def __truediv__(self, other: complex) -> complex: ...
+    @overload
+    def __rtruediv__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __rtruediv__(self, other: float) -> float: ...
+    @overload
+    def __rtruediv__(self, other: complex) -> complex: ...
+    if sys.version_info < (3, 0):
+        @overload
+        def __div__(self, other: Union[int, Fraction]) -> Fraction: ...
+        @overload
+        def __div__(self, other: float) -> float: ...
+        @overload
+        def __div__(self, other: complex) -> complex: ...
+        @overload
+        def __rdiv__(self, other: Union[int, Fraction]) -> Fraction: ...
+        @overload
+        def __rdiv__(self, other: float) -> float: ...
+        @overload
+        def __rdiv__(self, other: complex) -> complex: ...
+    @overload
+    def __floordiv__(self, other: Union[int, Fraction]) -> int: ...
+    @overload
+    def __floordiv__(self, other: float) -> float: ...
+    @overload
+    def __rfloordiv__(self, other: Union[int, Fraction]) -> int: ...
+    @overload
+    def __rfloordiv__(self, other: float) -> float: ...
+    @overload
+    def __mod__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __mod__(self, other: float) -> float: ...
+    @overload
+    def __rmod__(self, other: Union[int, Fraction]) -> Fraction: ...
+    @overload
+    def __rmod__(self, other: float) -> float: ...
+    @overload
+    def __divmod__(self, other: Union[int, Fraction]) -> Tuple[int, Fraction]: ...
+    @overload
+    def __divmod__(self, other: float) -> Tuple[float, Fraction]: ...
+    @overload
+    def __rdivmod__(self, other: Union[int, Fraction]) -> Tuple[int, Fraction]: ...
+    @overload
+    def __rdivmod__(self, other: float) -> Tuple[float, Fraction]: ...
+    @overload
+    def __pow__(self, other: int) -> Fraction: ...
+    @overload
+    def __pow__(self, other: Union[float, Fraction]) -> float: ...
+    @overload
+    def __pow__(self, other: complex) -> complex: ...
+    @overload
+    def __rpow__(self, other: Union[int, float, Fraction]) -> float: ...
+    @overload
+    def __rpow__(self, other: complex) -> complex: ...
+    def __pos__(self) -> Fraction: ...
+    def __neg__(self) -> Fraction: ...
+    def __abs__(self) -> Fraction: ...
+    def __trunc__(self) -> int: ...
+    if sys.version_info >= (3, 0):
+        def __floor__(self) -> int: ...
+        def __ceil__(self) -> int: ...
+        @overload
+        def __round__(self, ndigits: None = ...) -> int: ...
+        @overload
+        def __round__(self, ndigits: int) -> Fraction: ...
+    def __hash__(self) -> int: ...
+    def __eq__(self, other: object) -> bool: ...
+    def __lt__(self, other: _ComparableNum) -> bool: ...
+    def __gt__(self, other: _ComparableNum) -> bool: ...
+    def __le__(self, other: _ComparableNum) -> bool: ...
+    def __ge__(self, other: _ComparableNum) -> bool: ...
+    if sys.version_info >= (3, 0):
+        def __bool__(self) -> bool: ...
+    else:
+        def __nonzero__(self) -> bool: ...
+    # Not actually defined within fractions.py, but provides more useful
+    # overrides
+    @property
+    def real(self) -> Fraction: ...
+    @property
+    def imag(self) -> Literal[0]: ...
+    def conjugate(self) -> Fraction: ...