diff --git a/package.json b/package.json
index e83fa6dc7..f2cf54e90 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
   "license": "GPL-3.0",
   "devDependencies": {
     "@mate-academy/eslint-config": "*",
-    "@mate-academy/scripts": "^0.3.5",
+    "@mate-academy/scripts": "^1.2.12",
     "eslint": "^5.16.0",
     "eslint-plugin-jest": "^22.4.1",
     "eslint-plugin-node": "^8.0.1",
diff --git a/src/transformState.js b/src/transformState.js
index a1eaa0640..b9bffb5d4 100644
--- a/src/transformState.js
+++ b/src/transformState.js
@@ -5,7 +5,34 @@
  * @param {Object[]} actions
  */
 function transformState(state, actions) {
-  // write code here
+  if (Array.isArray(actions)) {
+    for (const action of actions) {
+      actionsObserver(state, action);
+    }
+
+    return;
+  }
+  actionsObserver(state, actions);
 }
 
 module.exports = transformState;
+
+const actionsObserver = (state, action) => {
+  switch (action.type) {
+    case 'addProperties':
+      Object.assign(state, action.extraData);
+      break;
+    case 'removeProperties':
+      for (const key of action.keysToRemove) {
+        delete state[key];
+      }
+      break;
+    case 'clear':
+      for (const key in state) {
+        delete state[key];
+      }
+      break;
+    default:
+      break;
+  }
+};