code: def test_propKB_tolerant():
      """ "tolerant to bad input"""
      kb = PropKB()
      A, B, C = symbols("A,B,C")
      assert kb.ask(B) is False
  
imports: from sympy.assumptions.ask import Q
  from sympy.core.symbol import symbols
  from sympy.core.relational import Unequality
  from sympy.logic.boolalg import And, Or, Implies, Equivalent, true, false
  from sympy.logic.inference import literal_symbol, pl_true, satisfiable, valid, entails, PropKB
  from sympy.logic.algorithms.dpll import dpll, dpll_satisfiable, find_pure_symbol, find_unit_clause, unit_propagate, find_pure_symbol_int_repr, find_unit_clause_int_repr, unit_propagate_int_repr
  from sympy.logic.algorithms.dpll2 import dpll_satisfiable
  from sympy.logic.algorithms.z3_wrapper import z3_satisfiable
  from sympy.assumptions.cnf import CNF, EncodedCNF
  from sympy.logic.tests.test_lra_theory import make_random_problem
  from sympy.core.random import randint
  from sympy.testing.pytest import raises, skip
  from sympy.external import import_module
label_desc: Use image node_id 19 for calling a global function with example usage: test_propKB_tolerant() without return types