diff --git a/Week04/functions_buse_demirbas.py b/Week04/functions_buse_demirbas.py
new file mode 100644
index 00000000..b967ae25
--- /dev/null
+++ b/Week04/functions_buse_demirbas.py
@@ -0,0 +1,28 @@
+import sys
+
+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:
+    """
+    Calculates (x**a + y**b) / c.
+    :param x: base x
+    :param y: base y
+    :param a: exp a
+    :param b: exp b
+    :param c: div c
+    :return: float result
+    """
+
+    if not all(isinstance(v, int) for v in (x, y, a, b, c)):
+        raise TypeError("Arguments must be integers")
+    return float((x**a + y**b) / c)
+
+
+def fn_w_counter() -> tuple[int, dict[str, int]]:
+
+    if not hasattr(fn_w_counter, "count"):
+        fn_w_counter.count = 0
+    
+    fn_w_counter.count += 1
+    module_name = __name__.split('.')[-1]
+    return fn_w_counter.count, {module_name: fn_w_counter.count}