code: public static ExpressionSimplifier lambdaCalculus() {
      List<ExpressionReplacementRule> rules = Lists.newArrayList();
      rules.add(new LambdaApplicationReplacementRule());
      rules.add(new VariableCanonicalizationReplacementRule());
      return new ExpressionSimplifier(rules);
    }
docs: Default simplifier for lambda calculus expressions. This
  simplifier performs beta reduction of lambda expressions
  and canonicalizes variable names.
  
  @return