diff --git a/Week04/decorators_sinem_tanriver.py b/Week04/decorators_sinem_tanriver.py
new file mode 100644
index 00000000..b162a5c8
--- /dev/null
+++ b/Week04/decorators_sinem_tanriver.py
@@ -0,0 +1,30 @@
+import time
+import tracemalloc
+from functools import wraps
+
+
+def performance(func):
+    """Measures time and memory of the decorated function and keeps statistics."""
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        started_here = not tracemalloc.is_tracing()
+        if started_here:
+            tracemalloc.start()
+        tracemalloc.reset_peak()
+        start = time.perf_counter()
+        result = func(*args, **kwargs)
+        elapsed = time.perf_counter() - start
+        _, peak = tracemalloc.get_traced_memory()
+        if started_here:
+            tracemalloc.stop()
+
+        performance.counter += 1
+        performance.total_time += elapsed
+        performance.total_mem += peak
+        return result
+    return wrapper
+
+
+performance.counter = 0
+performance.total_time = 0
+performance.total_mem = 0
diff --git a/Week04/functions_sinem_tanriver.py b/Week04/functions_sinem_tanriver.py
new file mode 100644
index 00000000..e06b68bd
--- /dev/null
+++ b/Week04/functions_sinem_tanriver.py
@@ -0,0 +1,32 @@
+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 the value of (x**a + y**b) / c.
+
+    :param x: First base, positional-only
+    :type x: int
+    :param y: Second base, positional-only
+    :type y: int
+    :param a: Exponent of x
+    :type a: int
+    :param b: Exponent of y
+    :type b: int
+    :param c: Divisor, keyword-only
+    :type c: int
+    :return: Result of (x**a + y**b) / c
+    :rtype: float
+    """
+    return (x ** a + y ** b) / c
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    caller = __name__
+    fn_w_counter.total += 1
+    fn_w_counter.callers[caller] = fn_w_counter.callers.get(caller, 0) + 1
+    return fn_w_counter.total, fn_w_counter.callers
+
+
+fn_w_counter.total = 0
+fn_w_counter.callers = {}