diff --git a/Week04/functions_yasin_soytas.py b/Week04/functions_yasin_soytas.py
new file mode 100644
index 00000000..9bbed1b7
--- /dev/null
+++ b/Week04/functions_yasin_soytas.py
@@ -0,0 +1,31 @@
+# ---------- custom_power ----------
+
+custom_power = lambda x, e=1: x ** e
+
+
+# ---------- custom_equation ----------
+
+def custom_equation(x, y=0, *, a=0, b=1, c=1) -> float:
+    """
+    Computes the equation: (x**a + y**b) / c
+    """
+    return (x ** a + y ** b) / c
+
+
+# ---------- fn_w_counter ----------
+
+def fn_w_counter():
+    total_calls = 0
+    callers = {}
+
+    def inner():
+        nonlocal total_calls
+        total_calls += 1
+
+        caller_name = __name__
+        callers[caller_name] = callers.get(caller_name, 0) + 1
+
+        return total_calls, callers
+
+    return inner
+