diff --git a/Week04/functions_turhan_gunduzoglu.py b/Week04/functions_turhan_gunduzoglu.py
new file mode 100644
index 00000000..6f3b6d32
--- /dev/null
+++ b/Week04/functions_turhan_gunduzoglu.py
@@ -0,0 +1,38 @@
+
+custom_power = lambda x, e=1: x ** e
+
+def custom_equation(x, y=0, /, a=0, *, b=1, c=1) -> float:
+    """
+    Calculate the value of (x**a + y**b) / c.
+
+    :param x: integer (positional-only)
+    :param y: integer (positional-only, default=0)
+    :param a: integer (positional or keyword, default=0)
+    :param b: integer (keyword-only, default=1)
+    :param c: integer (keyword-only, default=1)
+    :return: float
+    """
+    return (x ** a + y ** b) / c
+
+def fn_w_counter():
+    calls = {}
+
+    def inner(caller_name):
+        calls[caller_name] = calls.get(caller_name, 0) + 1
+        total_calls = sum(calls.values())
+        return total_calls, calls
+
+    return inner
+
+if __name__ == "__main__":
+    print(custom_power(2))          # 2
+    print(custom_power(2, 3))       # 8
+
+    print(custom_equation(2, 3))                # 5.0
+    print(custom_equation(2, 3, a=2, b=3, c=4))# 33.5
+
+    counter = fn_w_counter()
+    for _ in range(10):
+        counter("main")
+
+    print(counter("main"))  # (11, {'main': 11})