class_docstr: Box plot
  For each series, shows the median value, the 25th and 75th percentiles,
  and the values within
  1.5 times the interquartile range of the 25th and 75th percentiles.
  
  See http://en.wikipedia.org/wiki/Box_plot
docstr: Format value for dual value display.
code: def _value_format(self, value, serie):
      """
      Format value for dual value display.
      """
      if self.box_mode == "extremes":
          return "Min: %s\nQ1 : %s\nQ2 : %s\nQ3 : %s\nMax: %s" % tuple(
              map(self._y_format, serie.points[1:6])
          )
      elif self.box_mode in ["tukey", "stdev", "pstdev"]:
          return (
              "Min: %s\nLower Whisker: %s\nQ1: %s\nQ2: %s\nQ3: %s\n"
              "Upper Whisker: %s\nMax: %s"
              % tuple(map(self._y_format, serie.points))
          )
      elif self.box_mode == "1.5IQR":
          # 1.5IQR mode
          return "Q1: %s\nQ2: %s\nQ3: %s" % tuple(
              map(self._y_format, serie.points[2:5])
          )
      else:
          return self._y_format(serie.points)
  
file_path: pygal/pygal/graph/box.py
imports: from bisect import bisect_left, bisect_right
  from pygal.graph.graph import Graph
  from pygal.util import alter, decorate
label_desc: Use image node_id 1 for calling the Box obj's underlying member method code with example usage: obj._value_format(value, serie) and returns: unknown, unknown, unknown, self