def chars(self, start=(0, 0), end=None):
        if end is None:
            end = (1 - len(self), len(self[-1]))

        first_row, first_col = start
        last_row, last_col = end

        # XXX
        if first_row == last_row:
            return self[first_row][first_col:last_col]

        first = self[first_row][first_col:]
        middle = itertools.chain.from_iterable(self[first_row + 1:last_row])
        last = self[last_row][:last_col]

        return itertools.chain(first, middle, last)
dataset/ETHPy150Open Julian/PyVi/pyvi/window.py/Buffer.chars/swapped operands of `-`