class_docstr: XY Line graph class
docstr: Getter for the maximum series value
code: def _max(self):
      """Getter for the maximum series value"""
      return (
          self.range[1]
          if (self.range and self.range[1] is not None)
          else (max(self.yvals) if self.yvals else None)
      )
  
file_path: pygal/pygal/graph/xy.py
imports: from functools import reduce
  from pygal.graph.dual import Dual
  from pygal.graph.line import Line
  from pygal.util import cached_property, compose, ident
label_desc: Use image node_id 4 for calling the XY obj's underlying member method code with example usage: obj._max() and returns: unknown