code: function defineProperties(obj) {
      Object.defineProperties(obj, {
          "pre": {
              value: Contract.pre,
              configurable: true
          },
          "post": {
              value: Contract.post,
              configurable: true
          },
          "invariant": {
              value: Contract.invariant,
              configurable: true
          }
      });
  }
docs: Define the pre, post & invariant objects onto an object.