code: function notEvaluator(conditions, leafEvaluator) {
    if (conditions.length > 0) {
      var result = evaluate(conditions[0], leafEvaluator);
      return result === null ? null : !result;
    }
    return null;
  }
docs: Evaluates an array of conditions as if the evaluator had been applied
  to a single entry and NOT was applied to the result.
  @param  {Array}      conditions      Array of conditions ex: [operand_1]
  @param  {Function}   leafEvaluator   Function which will be called to evaluate leaf condition values
  @return {?Boolean}                   Result of evaluating the conditions. A return value of null
  indicates that the conditions are invalid or unable to be
  evaluated.