def adjust_frame(self, pos, absolute_pos):
        """Adjust stack frame by pos positions. If absolute_pos then
        pos is an absolute number. Otherwise it is a relative number.

        A negative number indexes from the other end."""
        if not self.curframe:
            Mmsg.errmsg(self, "No stack.")
            return

        # Below we remove any negativity. At the end, pos will be
        # the new value of self.curindex.
        if absolute_pos:
            if pos >= 0:
                pos = len(self.stack)-pos-1
            else:
                pos = -pos-1
        else:
            pos += self.curindex

        if pos < 0:
            Mmsg.errmsg(self,
                        "Adjusting would put us beyond the oldest frame.")
            return
        elif pos >= len(self.stack):
            Mmsg.errmsg(self,
                        "Adjusting would put us beyond the newest frame.")
            return

        self.curindex = pos
        self.curframe = self.stack[self.curindex][0]
        self.print_location()
        self.list_lineno = None
        return
Adjust stack frame by pos positions. If absolute_pos then
        pos is an absolute number. Otherwise it is a relative number.

        A negative number indexes from the other end.