code: def render_sparktext(self, relative_to=None):
          
          bars = u('▁▂▃▄▅▆▇█')
          if len(self.raw_series) == 0:
              return u('')
          values = list(self.raw_series[0][0])
          if len(values) == 0:
              return u('')
  
          chart = u('')
          values = list(map(lambda x: max(x, 0), values))
  
          vmax = max(values)
          if relative_to is None:
              relative_to = min(values)
  
          if (vmax - relative_to) == 0:
              chart = bars[0] * len(values)
              return chart
  
          divisions = len(bars) - 1
          for value in values:
              chart += bars[int(
                  divisions * (value - relative_to) / (vmax - relative_to)
              )]
          return chart
docs: Make a mini text sparkline from chart