code: def _groupDefinition(self, group):
      name = self._className(group.name)
      glyphs = self._enum(group.enum)
      glyphclass = ast.GlyphClassDefinition(name, glyphs)
  
      self._glyphclasses[group.name.lower()] = glyphclass
  
imports: import logging
  import re
  from io import StringIO
  from fontTools.feaLib import ast
  from fontTools.ttLib import TTFont, TTLibError
  from fontTools.voltLib import ast
  from fontTools.voltLib.parser import Parser
label_desc: Use image node_id 12 for calling the VoltToFea obj's underlying member method code with example usage: obj._groupDefinition(group) without return types