code: def _attempt_proof_eq(
      self, current, context, agenda, accessible_vars, atoms, debug
  ):
      #########################################################################
      # Since 'current' is of the form '(a = b)', replace ALL free instances
      # of 'a' with 'b'
      #########################################################################
      agenda.put_atoms(atoms)
      agenda.replace_all(current.first, current.second)
      accessible_vars.discard(current.first)
      agenda.mark_neqs_fresh()
      return self._attempt_proof(
          agenda, accessible_vars, set(), debug + 1
      )
  
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 21 for calling the TableauProver obj's underlying member method code with example usage: obj._attempt_proof_eq(current, context, agenda, accessible_vars, atoms, debug) and returns: self