    def deltas(self, start, height):
        """
        Return a list-like (i.e. iterable) object of (y, x) tuples
        """
        for y in range(start, min(start + height, self._height)):
            for x in range(self._width):
                old_cell = self._screen_buffer[y][x]
                new_cell = self._double_buffer[y][x]
                if old_cell != new_cell:
                    yield y, x
Return a list-like (i.e. iterable) object of (y, x) tuples
asciimatics/screen.py