code: def _plot(self):
          
          total = sum(map(sum, map(lambda x: x.values, self.series)))
          if total == 0:
              return
          if self.half_pie:
              current_angle = 3 * pi / 2
          else:
              current_angle = 0
  
          for index, serie in enumerate(self.series):
              angle = self.slice(serie, current_angle, total)
              current_angle += angle
docs: Draw all the serie slices