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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _setup_bar(self):
 """ Setup the process bar. """

        bar = u""
        items_cnt = len(PROGRESS_BAR_ITEMS)
        bar_val = float(self._time_left) / self._section_time * self.num_progress_bars
        while bar_val > 0:
            selector = int(bar_val * items_cnt)
            selector = min(selector, items_cnt - 1)
            bar += PROGRESS_BAR_ITEMS[selector]
            bar_val -= 1

        bar = bar.ljust(self.num_progress_bars)
        return bar