diff --git a/Week04/functions_burakcan_aksoy.py b/Week04/functions_burakcan_aksoy.py
new file mode 100644
index 00000000..d172b848
--- /dev/null
+++ b/Week04/functions_burakcan_aksoy.py
@@ -0,0 +1,51 @@
+# custom_power: A lambda function
+# - Two parameters (x and e)
+# - x is positional-only
+# - e is positional-or-keyword
+# - x has default value 0
+# - e has default value 1
+# - Returns x**e
+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:
+    """
+    A custom equation that calculates (x**a + y**b) / c
+    
+    :param x: First integer value (positional-only, default 0)
+    :param y: Second integer value (positional-only, default 0)
+    :param a: Exponent for x (positional-or-keyword, default 1)
+    :param b: Exponent for y (positional-or-keyword, default 1)
+    :param c: Divisor (keyword-only, default 1)
+    :return: The result of (x**a + y**b) / c as a float
+    """
+    # Type checking
+    if not isinstance(x, int) or isinstance(x, bool):
+        raise TypeError("x must be an integer")
+    if not isinstance(y, int) or isinstance(y, bool):
+        raise TypeError("y must be an integer")
+    if not isinstance(a, int) or isinstance(a, bool):
+        raise TypeError("a must be an integer")
+    if not isinstance(b, int) or isinstance(b, bool):
+        raise TypeError("b must be an integer")
+    if not isinstance(c, int) or isinstance(c, bool):
+        raise TypeError("c must be an integer")
+    
+    return (x ** a + y ** b) / c
+
+
+# fn_w_counter: A function that counts calls
+# - Returns a tuple of (call_count, {module_name: call_count})
+# - Uses a closure to maintain state
+_counter = 0
+_module_name = __name__
+
+def fn_w_counter() -> (int, dict[str, int]):
+    """
+    A function that counts the number of times it has been called.
+    
+    :return: A tuple containing the call count and a dictionary with module info
+    """
+    global _counter
+    _counter += 1
+    return (_counter, {_module_name: _counter})