docs: function difference(a, b) {
    var oldHashes = {};
    var errors = [];
    var _iteratorNormalCompletion = true;
    var _didIteratorError = false;
    var _iteratorError = undefined;
  
    try {
      for (var _iterator = b.errors[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
        var error = _step.value;
  
        var hash = JSON.stringify(error.message);
        oldHashes[hash] = error;
      }
    } catch (err) {
      _didIteratorError = true;
      _iteratorError = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion && _iterator.return) {
          _iterator.return();
        }
      } finally {
        if (_didIteratorError) {
          throw _iteratorError;
        }
      }
    }
  
    var _iteratorNormalCompletion2 = true;
    var _didIteratorError2 = false;
    var _iteratorError2 = undefined;
  
    try {
      for (var _iterator2 = a.errors[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
        var _error = _step2.value;
  
        var _hash = JSON.stringify(_error.message);
        if (oldHashes[_hash] !== undefined) {
          continue;
        }
        errors.push(JSON.parse(JSON.stringify(_error)));
      }
    } catch (err) {
      _didIteratorError2 = true;
      _iteratorError2 = err;
    } finally {
      try {
        if (!_iteratorNormalCompletion2 && _iterator2.return) {
          _iterator2.return();
        }
      } finally {
        if (_didIteratorError2) {
          throw _iteratorError2;
        }
      }
    }
  
    return {
      passed: errors.length === 0,
      errors: errors,
      flowVersion: a.flowVersion
    };
  }