code: def describe(self):
      if not self.neg:
          return f"{self.on} = {self.at}"
      else:
          return f"{self.on} ≠ {self.at}"
  
imports: from __future__ import annotations
  import abc
  import copy
  import math
  import numbers
  import typing
  from river import base, tree
label_desc: Use image node_id 3 for calling the NominalLiteral obj's underlying member method code with example usage: obj.describe() and returns: self, str, self, self, str, self