How to use the birdears.urwid.compat.xrange function in birdears

XX..
        """
        sx, sy = self.constrain_coords(*start)
        ex, ey = self.constrain_coords(*end)

        # within a single row
        if sy == ey:
            for x in xrange(sx, ex + 1):
                self.term[sy][x] = self.empty_char()
            return

        # spans multiple rows
        y = sy
        while y <= ey:
            if y == sy:
                for x in xrange(sx, self.width):
                    self.term[y][x] = self.empty_char()
            elif y == ey:
                for x in xrange(ex + 1):
                    self.term[y][x] = self.empty_char()
            else:
                self.blank_line(y)

            y += 1

Erase a region of the terminal. The 'start' tuple (x, y) defines the
        starting position of the erase, while end (x, y) the last position.

        For example if the terminal size is 4x3, start=(1, 1) and end=(1, 2)
        would erase the following region:

        ....
        .XXX
        XX..
        """
        sx, sy = self.constrain_coords(*start)
        ex, ey = self.constrain_coords(*end)

        # within a single row
        if sy == ey:
            for x in xrange(sx, ex + 1):
                self.term[sy][x] = self.empty_char()
            return

        # spans multiple rows
        y = sy
        while y <= ey:
            if y == sy:
                for x in xrange(sx, self.width):
                    self.term[y][x] = self.empty_char()
            elif y == ey:
                for x in xrange(ex + 1):
                    self.term[y][x] = self.empty_char()
            else:
                self.blank_line(y)

            y += 1

def _setup_colour_pairs(self):
        """
        Initialize all 63 color pairs based on the term:
        bg * 8 + 7 - fg
        So to get a color, we just need to use that term and get the right color
        pair number.
        """
        if not self.has_color:
            return

        for fg in xrange(8):
            for bg in xrange(8):
                # leave out white on black
                if fg == curses.COLOR_WHITE and \
                   bg == curses.COLOR_BLACK:
                    continue

                curses.init_pair(bg * 8 + 7 - fg, fg, bg)

focus = self._validate_contents_modified(indices, new_items)
        if focus is not None:
            return focus

        focus = self._focus
        if step == 1:
            if start + num_new_items <= focus < stop:
                focus = stop
            # adjust for added/removed items
            if stop <= focus:
                focus += num_new_items - (stop - start)

        else:
            if not num_new_items:
                # extended slice being removed
                if focus in xrange(start, stop, step):
                    focus += 1

                # adjust for removed items
                focus -= len(list(xrange(start, min(focus, stop), step)))

        return min(focus, len(self) + num_new_items - num_removed -1)

ex, ey = self.constrain_coords(*end)

        # within a single row
        if sy == ey:
            for x in xrange(sx, ex + 1):
                self.term[sy][x] = self.empty_char()
            return

        # spans multiple rows
        y = sy
        while y <= ey:
            if y == sy:
                for x in xrange(sx, self.width):
                    self.term[y][x] = self.empty_char()
            elif y == ey:
                for x in xrange(ex + 1):
                    self.term[y][x] = self.empty_char()
            else:
                self.blank_line(y)

            y += 1

def clear(self, cursor=None):
        """
        Clears the whole terminal screen and resets the cursor position
        to (0, 0) or to the coordinates given by 'cursor'.
        """
        self.term = [self.empty_line() for x in xrange(self.height)]

        if cursor is None:
            self.set_term_cursor(0, 0)
        else:
            self.set_term_cursor(*cursor)

def reverse_video(self, undo=False):
        """
        Reverse video/scanmode (DECSCNM) by swapping fg and bg colors.
        """
        for y in xrange(self.height):
            for x in xrange(self.width):
                char = self.term[y][x]
                attrs = self.reverse_attrspec(char[0], undo=undo)
                self.term[y][x] = (attrs,) + char[1:]

def __iter__(self):
        """
        Return an iterable of positions for this container from first
        to last.
        """
        return iter(xrange(len(self.contents)))