def keys(self):
        if self.headingrow is not None:
            return self.sheet_row(self.headingrow)
        else:
            u = string.ascii_uppercase
            return [''.join(r) for idx, r in
                    enumerate(itertools.chain(u, itertools.product(u, u)))
                    if idx < self.num_cols()]
dataset/ETHPy150Open kristianperkins/x_x/x_x/cursor.py/XCursor.keys/original