All tasks completed

.eslintignore

@@ -1,2 +1 @@
 node_modules/
-Exercises/

Exercises/.prettierrc

@@ -0,0 +1,7 @@
+{
+    "trailingComma": "es5",
+    "tabWidth": 2,
+    "semi": true,
+    "singleQuote": true,
+    "space-before-function-paren": ["error", "never"]
+}

Exercises/1-callback.js

@@ -1,5 +1,11 @@
 'use strict';
 
-const iterate = (obj, callback) => null;
+const iterate = (obj, callback) => {
+  const keys = Object.keys(obj);
+  for (const key of keys) {
+    const element = obj[key];
+    callback(key, element, obj);
+  }
+};
 
 module.exports = { iterate };

Exercises/2-closure.js

@@ -1,5 +1,5 @@
 'use strict';
 
-const store = (x) => null;
+const store = (x) => () => x;
 
 module.exports = { store };

Exercises/3-wrapper.js

@@ -1,5 +1,23 @@
 'use strict';
+// prettier-ignore
+const contract =
+  (fn, ...types) =>
+    (...args) => {
+      for (let i = 0; i < args; i++) {
+        const type = types[i];
+        const arg = args[i];
+        if (typeof arg !== type.name.toLowerCase()) {
+          throw new TypeError('Types do not match');
+        }
+      }
 
-const contract = (fn, ...types) => null;
+      const result = fn(...args);
+      const type = types.at(-1);
+      if (typeof result !== type.name.toLowerCase()) {
+        throw new TypeError('Types do not match');
+      }
+
+      return result;
+    };
 
 module.exports = { contract };