class_docstr: Stacked Line graph class
docstr: Plot stacked serie lines and stacked secondary lines
code: def _plot(self):
      """Plot stacked serie lines and stacked secondary lines"""
      for serie in self.series[:: -1 if self.stack_from_top else 1]:
          self.line(serie)
      for serie in self.secondary_series[
          :: -1 if self.stack_from_top else 1
      ]:
          self.line(serie, True)
  
file_path: pygal/pygal/graph/stackedline.py
imports: from pygal.adapters import none_to_zero
  from pygal.graph.line import Line
label_desc: Use image node_id 5 for calling the StackedLine obj's underlying member method code with example usage: obj._plot() without return types