def copy(self, deep: bool = True, data: T_DuckArray | ArrayLike | None = None):
        """Returns a copy of this object.

        `deep` is ignored since data is stored in the form of
        pandas.Index, which is already immutable. Dimensions, attributes
        and encodings are always copied.

        Use `data` to create a new object with the same structure as
        original but entirely new data.

        Parameters
        ----------
        deep : bool, default: True
            Deep is ignored when data is given. Whether the data array is
            loaded into memory and copied onto the new object. Default is True.
        data : array_like, optional
            Data to use in the new object. Must have same shape as original.

        Returns
        -------
        object : Variable
            New object with dimensions, attributes, encodings, and optionally
            data copied from original.
        """
        if data is None:
            ndata = self._data

            if deep:
                ndata = copy.deepcopy(ndata, None)

        else:
            ndata = as_compatible_data(data)
            if self.shape != ndata.shape:  # type: ignore[attr-defined]
                raise ValueError(
                    f"Data shape {ndata.shape} must match shape of object {self.shape}"  # type: ignore[attr-defined]
                )

        attrs = copy.deepcopy(self._attrs) if deep else copy.copy(self._attrs)
        encoding = copy.deepcopy(self._encoding) if deep else copy.copy(self._encoding)

        return self._replace(data=ndata, attrs=attrs, encoding=encoding)
Returns a copy of this object.

        `deep` is ignored since data is stored in the form of
        pandas.Index, which is already immutable. Dimensions, attributes
        and encodings are always copied.

        Use `data` to create a new object with the same structure as
        original but entirely new data.

        Parameters
        ----------
        deep : bool, default: True
            Deep is ignored when data is given. Whether the data array is
            loaded into memory and copied onto the new object. Default is True.
        data : array_like, optional
            Data to use in the new object. Must have same shape as original.

        Returns
        -------
        object : Variable
            New object with dimensions, attributes, encodings, and optionally
            data copied from original.
        
xarray/core/variable.py