code: def __getitem__(self, index):
      return self.sets[index]
  
imports: from nltk.inference.api import BaseProverCommand, Prover
  from nltk.internals import Counter
  from nltk.sem.logic import AbstractVariableExpression, AllExpression, AndExpression, ApplicationExpression, EqualityExpression, ExistsExpression, Expression, FunctionVariableExpression, IffExpression, ImpExpression, LambdaExpression, NegatedExpression, OrExpression, Variable, VariableExpression, unique_variable
label_desc: Use image node_id 3 for calling the Agenda obj's underlying member method code with example usage: obj.__getitem__(index) and returns: self