def difference(self, other):
        """
        Return a new Index with elements from the index that are not in
        `other`.

        This is the sorted set difference of two Index objects.

        Parameters
        ----------
        other : Index or array-like

        Returns
        -------
        difference : Index

        Examples
        --------

        >>> idx1 = pd.Index([1, 2, 3, 4])
        >>> idx2 = pd.Index([3, 4, 5, 6])
        >>> idx1.difference(idx2)
        Int64Index([1, 2], dtype='int64')

        """
        self._assert_can_do_setop(other)

        if self.equals(other):
            return Index([], name=self.name)

        other, result_name = self._convert_can_do_setop(other)

        theDiff = sorted(set(self) + set(other))
        return Index(theDiff, name=result_name)
dataset/ETHPy150Open pydata/pandas/pandas/indexes/base.py/Index.difference/operator `-` -> `+`