diff --git a/kala-base/src/main/java/kala/collection/base/primitive/PrimitiveMapIterator.java b/kala-base/src/main/java/kala/collection/base/primitive/PrimitiveMapIterator.java
new file mode 100644
index 00000000..431c8747
--- /dev/null
+++ b/kala-base/src/main/java/kala/collection/base/primitive/PrimitiveMapIterator.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 Glavo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package kala.collection.base.primitive;
+
+import kala.collection.base.MapIterator;
+
+public interface PrimitiveMapIterator<K, V> extends MapIterator<K, V> {
+
+}
diff --git a/src/test/java/kala/control/OptionTest.java b/src/test/java/kala/control/OptionTest.java
index e38c1f35..28d0742f 100644
--- a/src/test/java/kala/control/OptionTest.java
+++ b/src/test/java/kala/control/OptionTest.java
@@ -1,33 +1,48 @@
-package kala.control;
-
-import org.junit.jupiter.api.*;
-
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
-import java.util.Arrays;
-
-import static org.junit.jupiter.api.Assertions.*;
-
-public class OptionTest {
-    Option<?>[] opts = new Option<?>[]{
-            Option.none(),
-            Option.some("foo"),
-            Option.some(10),
-            Option.some(Arrays.asList("A", "B", "C")),
-            Option.some(null)
-    };
-
-    @Test
-    public void serializationTest() {
-        assertAll(Arrays.stream(opts).map(opt -> () -> {
-            ByteArrayOutputStream out = new ByteArrayOutputStream(512);
-            new ObjectOutputStream(out).writeObject(opt);
-            byte[] buffer = out.toByteArray();
-            ByteArrayInputStream in = new ByteArrayInputStream(buffer);
-            Object obj = new ObjectInputStream(in).readObject();
-            assertEquals(opt, obj);
-        }));
-    }
-}
+/*
+ * Copyright 2024 Glavo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package kala.control;
+
+import org.junit.jupiter.api.*;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class OptionTest {
+    Option<?>[] opts = new Option<?>[]{
+            Option.none(),
+            Option.some("foo"),
+            Option.some(10),
+            Option.some(Arrays.asList("A", "B", "C")),
+            Option.some(null)
+    };
+
+    @Test
+    public void serializationTest() {
+        assertAll(Arrays.stream(opts).map(opt -> () -> {
+            ByteArrayOutputStream out = new ByteArrayOutputStream(512);
+            new ObjectOutputStream(out).writeObject(opt);
+            byte[] buffer = out.toByteArray();
+            ByteArrayInputStream in = new ByteArrayInputStream(buffer);
+            Object obj = new ObjectInputStream(in).readObject();
+            assertEquals(opt, obj);
+        }));
+    }
+}
diff --git a/src/test/java/kala/control/primitive/BooleanOptionTest.java b/src/test/java/kala/control/primitive/BooleanOptionTest.java
index d3d46f2f..b6012769 100644
--- a/src/test/java/kala/control/primitive/BooleanOptionTest.java
+++ b/src/test/java/kala/control/primitive/BooleanOptionTest.java
@@ -1,26 +1,40 @@
-package kala.control.primitive;
-
-import kala.control.primitive.BooleanOption;
-import org.junit.jupiter.api.Test;
-
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
-import java.util.stream.Stream;
-
-import static org.junit.jupiter.api.Assertions.*;
-
-public class BooleanOptionTest {
-    @Test
-    public void serializationTest() {
-        assertAll(Stream.of(BooleanOption.True, BooleanOption.False, BooleanOption.None).map(opt -> () -> {
-            ByteArrayOutputStream out = new ByteArrayOutputStream(512);
-            new ObjectOutputStream(out).writeObject(opt);
-            byte[] buffer = out.toByteArray();
-            ByteArrayInputStream in = new ByteArrayInputStream(buffer);
-            Object obj = new ObjectInputStream(in).readObject();
-            assertSame(opt, obj);
-        }));
-    }
-}
+/*
+ * Copyright 2024 Glavo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package kala.control.primitive;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class BooleanOptionTest {
+    @Test
+    public void serializationTest() {
+        assertAll(Stream.of(BooleanOption.True, BooleanOption.False, BooleanOption.None).map(opt -> () -> {
+            ByteArrayOutputStream out = new ByteArrayOutputStream(512);
+            new ObjectOutputStream(out).writeObject(opt);
+            byte[] buffer = out.toByteArray();
+            ByteArrayInputStream in = new ByteArrayInputStream(buffer);
+            Object obj = new ObjectInputStream(in).readObject();
+            assertSame(opt, obj);
+        }));
+    }
+}