code: def asFea(self, indent=""):
      res = ""
      if not getattr(self, "used", False):
          res += "#"
      res += ast.MarkClassDefinition.asFea(self, indent)
      return res
  
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 1 for calling the MarkClassDefinition obj's underlying member method code with example usage: obj.asFea(indent) and returns: res