diff --git a/Week04/decorators_yunus_dermencioglu.py b/Week04/decorators_yunus_dermencioglu.py
new file mode 100644
index 00000000..311e7e17
--- /dev/null
+++ b/Week04/decorators_yunus_dermencioglu.py
@@ -0,0 +1,32 @@
+import time
+import tracemalloc
+from functools import wraps
+
+
+def performance(func):
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+
+        tracemalloc.start()
+        start_time = time.perf_counter()
+
+        try:
+            result = func(*args, **kwargs)
+        finally:
+            elapsed_time = time.perf_counter() - start_time
+            current, peak = tracemalloc.get_traced_memory()
+            tracemalloc.stop()
+
+            performance.counter += 1
+            performance.total_time += elapsed_time
+            performance.total_mem += peak
+
+        return result
+
+    return wrapper
+
+
+performance.counter = 0
+performance.total_time = 0.0
+performance.total_mem = 0
diff --git a/Week04/functions_yunus_dermencioglu.py b/Week04/functions_yunus_dermencioglu.py
new file mode 100644
index 00000000..25c10cdb
--- /dev/null
+++ b/Week04/functions_yunus_dermencioglu.py
@@ -0,0 +1,39 @@
+import inspect
+
+custom_power = lambda x=0, /, e=1: x ** e
+
+
+def custom_equation(
+    x: int = 0,
+    y: int = 0,
+    /,
+    a: int = 1,
+    b: int = 1,
+    *,
+    c: int = 1
+) -> float:
+    """
+    Calculate the result of the equation.
+
+    :param x: First integer.
+    :param y: Second integer.
+    :param a: Exponent of x.
+    :param b: Exponent of y.
+    :param c: Divisor.
+    :return: The calculated result.
+    :rtype: float
+    """
+    return float((x ** a + y ** b) / c)
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    if not hasattr(fn_w_counter, "counts"):
+        fn_w_counter.counts = {}
+
+    caller_name = fn_w_counter.__module__
+
+    counts = fn_w_counter.counts
+    counts[caller_name] = counts.get(caller_name, 0) + 1
+
+    return sum(counts.values()), counts.copy()
+