diff --git a/Week04/functions_elif_yalvac.py b/Week04/functions_elif_yalvac.py
new file mode 100644
index 00000000..67838e73
--- /dev/null
+++ b/Week04/functions_elif_yalvac.py
@@ -0,0 +1,30 @@
+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 a specific mathematical expression.
+
+    :param x: Positional-only, default 0
+    :param y: Positional-only, default 0
+    :param a: Positional or keyword, default 1
+    :param b: Positional or keyword, default 1
+    :param c: Keyword-only, default 1
+    :return: Returns (x**a + y**b) / c as a float
+    """
+    return (x ** a + y ** b) / c
+
+
+
+
+from collections import defaultdict
+import inspect
+_total_calls = 0
+_caller_counts = defaultdict(int)
+def fn_w_counter() -> tuple[int, dict[str, int]]:
+    global _total_calls
+    _total_calls += 1
+    caller = inspect.currentframe().f_back.f_globals.get('__name__', '<unknown>')
+    _caller_counts[caller] += 1
+    return _total_calls, dict(_caller_counts)