code: def __init__(self, prob, *args, **kwargs):
      TreeEdge.__init__(self, *args, **kwargs)
      self._prob = prob
      # two edges with different probabilities are not equal.
      self._comparison_key = (self._comparison_key, prob)
  
imports: import random
  from functools import reduce
  from nltk.grammar import PCFG, Nonterminal
  from nltk.parse.api import ParserI
  from nltk.parse.chart import AbstractChartRule, Chart, LeafEdge, TreeEdge
  from nltk.tree import ProbabilisticTree, Tree
label_desc: Use image node_id 1 to create a new ProbabilisticTreeEdge object from inherited base classes: TreeEdge with example: obj = ProbabilisticTreeEdge(prob)