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diff --git a/addon-sdk/source/lib/sdk/util/contract.js b/addon-sdk/source/lib/sdk/util/contract.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "unstable"
+};
+
+const { validateOptions: valid } = require("../deprecated/api-utils");
+const method = require("method/core");
+
+// Function takes property validation rules and returns function that given
+// an `options` object will return validated / normalized options back. If
+// option(s) are invalid validator will throw exception described by rules.
+// Returned will also have contain `rules` property with a given validation
+// rules and `properties` function that can be used to generate validated
+// property getter and setters can be mixed into prototype. For more details
+// see `properties` function below.
+function contract(rules) {
+  const validator = (instance, options) => {
+    return valid(options || instance || {}, rules);
+  };
+  validator.rules = rules
+  validator.properties = function(modelFor) {
+    return properties(modelFor, rules);
+  }
+  return validator;
+}
+exports.contract = contract
+
+// Function takes `modelFor` instance state model accessor functions and
+// a property validation rules and generates object with getters and setters
+// that can be mixed into prototype. Property accessors update model for the
+// given instance. If you wish to react to property updates you can always
+// override setters to put specific logic.
+function properties(modelFor, rules) {
+  let descriptor = Object.keys(rules).reduce(function(descriptor, name) {
+    descriptor[name] = {
+      get: function() { return modelFor(this)[name] },
+      set: function(value) {
+        let change = {};
+        change[name] = value;
+        modelFor(this)[name] = valid(change, rules)[name];
+      }
+    }
+    return descriptor
+  }, {});
+  return Object.create(Object.prototype, descriptor);
+}
+exports.properties = properties;
+
+const validate = method("contract/validate");
+exports.validate = validate;