def __init__(
            self, 
            value: Optional[object] = None, 
            active: bool = True, 
            flag: str = "default",
        ) -> None:
        """
        Constructor for the ``Variable`` class.

        Parameters
        ----------
        value : object, None
            Value the decision variable is to take.
        active : bool
            Whether the variable is active (``True``) or inactive (``False``).
        flag : str
            Flag to bind to the decision variable.
        """
        super().__init__()
        self.value = value
        self.flag = flag
        self.active = active

        Constructor for the ``Variable`` class.

        Parameters
        ----------
        value : object, None
            Value the decision variable is to take.
        active : bool
            Whether the variable is active (``True``) or inactive (``False``).
        flag : str
            Flag to bind to the decision variable.
        
pymoo/core/variable.py