setter.py

from typing import NamedTuple, Tuple, Union


class ConsoleDimensions(NamedTuple):
    width: int
    height: int


class TestClass:
    def __init__(self) -> None:
        self._width = 3
        self._height = 4

    @property
    def size(self) -> Union[ConsoleDimensions, Tuple[int, int]]:
        return ConsoleDimensions(self._width, self._height)

    @size.setter
    def size(self, new_size: Tuple[int, int]) -> None:
        width, height = new_size
        self._width = width
        self._height = height


a = TestClass()
a.size = (4, 5)