diff --git a/Week04/decorators_rafet_taskin.py b/Week04/decorators_rafet_taskin.py
new file mode 100644
index 00000000..f6f6cad3
--- /dev/null
+++ b/Week04/decorators_rafet_taskin.py
@@ -0,0 +1,27 @@
+import time
+import tracemalloc
+import functools
+
+def performance(func):
+    @functools.wraps(func) # Preserve metadata of the original function
+    def wrapper(*args, **kwargs):
+        tracemalloc.start()
+        start_time = time.time()
+        
+        try:
+            result = func(*args, **kwargs)
+        finally:
+            current, peak = tracemalloc.get_traced_memory()
+            tracemalloc.stop()
+            end_time = time.time()
+            
+            performance.counter += 1
+            performance.total_time += (end_time - start_time)
+            performance.total_mem += peak
+            
+        return result
+    return wrapper
+
+performance.counter = 0
+performance.total_time = 0
+performance.total_mem = 0
diff --git a/Week04/functions_rafet_taskin.py b/Week04/functions_rafet_taskin.py
new file mode 100644
index 00000000..f9052da3
--- /dev/null
+++ b/Week04/functions_rafet_taskin.py
@@ -0,0 +1,27 @@
+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:
+    """
+    Computes a custom equation.
+    
+    :param x: First base (positional only)
+    :param y: Second base (positional only)
+    :param a: First exponent
+    :param b: Second exponent
+    :param c: Divisor (keyword only)
+    :return: The result of (x^a + y^b) / c
+    """
+    
+    for param_name, value in [('x', x), ('y', y), ('a', a), ('b', b), ('c', c)]:
+        if not isinstance(value, int):
+            raise TypeError(f"{param_name} must be an integer")
+
+    return float((x ** a + y ** b) / c)
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    if not hasattr(fn_w_counter, "count"):
+        fn_w_counter.count = 0
+    
+    fn_w_counter.count += 1
+    
+    return fn_w_counter.count, {__name__: fn_w_counter.count}