def draw_progress(self):
        total = 1 if self.nb_total == 0 else self.nb_total
        percent_done  = (self.nb_done / total) * 100
        percent_error = (self.nb_error / total) * 100
        percent_total = percent_done + percent_error
        nb_done_and_error = self.nb_done + self.nb_error
        ratio = (percent_total / 100) * self.progress_size
        width = math.floor(ratio)
        empty = self.progress_size - width - 1

        slice_char = "" if empty < 0 else self.chars[math.floor((ratio % 1) * len(self.chars))]
        bar   = '[{0}{1}]'.format('█' * width + slice_char, ' ' * empty)