class_docstr: Histogram chart class
class_docstr_tok: ["Histogram","chart","class"]
docstr: Getter for secondary series values (flattened)
docstr_tok: ["Getter","for","secondary","series","values","(","flattened",")"]
code: def _secondary_values(self):
      """Getter for secondary series values (flattened)"""
      return [
          val[0]
          for serie in self.secondary_series
          for val in serie.values
          if val[0] is not None
      ]
  
file_path: pygal/pygal/graph/histogram.py
imports: from pygal.graph.bar import Bar
  from pygal.graph.dual import Dual
  from pygal.util import alter, cached_property, decorate
label_desc: Use image node_id 2 for calling the Histogram obj's underlying member method code with example usage: obj._secondary_values() and returns: unknown