diff --git a/Week04/functions_esra_kaya.py b/Week04/functions_esra_kaya.py
new file mode 100644
index 00000000..537bccf5
--- /dev/null
+++ b/Week04/functions_esra_kaya.py
@@ -0,0 +1,38 @@
+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:
+    """
+    This function calculates a custom equation that.
+
+    :param x: Positional-only parameter, default value is 0.
+    :param y: Positional-only parameter, default value is 0.
+    :param a: Exponent for `x`, default value is 1.
+    :param b: Exponent for `y`, default value is 1.
+    :param c: Divisor of the equation, default value is 1.
+    
+    :type x: int
+    :type y: int
+    :type a: int
+    :type b: int
+    :type c: int
+
+    :return: The result of the custom equation ((x^a)+(y^b))/c.
+    :rtype: float
+    """
+    return (x**a + y**b) / c
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    if not hasattr(fn_w_counter, "call_counter"):
+        fn_w_counter.call_counter = 0
+        fn_w_counter.caller_counts = {}
+
+    caller = __name__
+    fn_w_counter.call_counter += 1
+
+    if caller not in fn_w_counter.caller_counts:
+        fn_w_counter.caller_counts[caller] = 1
+    else:
+        fn_w_counter.caller_counts[caller] += 1
+
+    return fn_w_counter.call_counter, fn_w_counter.caller_counts