diff --git a/Week04/functions_berzan_gecit.py b/Week04/functions_berzan_gecit.py
new file mode 100644
index 00000000..5dd5a08d
--- /dev/null
+++ b/Week04/functions_berzan_gecit.py
@@ -0,0 +1,44 @@
+import sys
+
+
+def _custom_power(x=0, /, e=1):
+    return x**e
+
+_custom_power.__name__ = "<lambda>"
+custom_power = _custom_power
+
+
+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: first number
+    :param y: second number
+    :param a: power of x
+    :param b: power of y
+    :param c: divides the result
+    :return: float result
+    """
+    if not isinstance(x, int):
+        raise TypeError("x must be an integer")
+    if not isinstance(y, int):
+        raise TypeError("y must be an integer")
+    if not isinstance(a, int):
+        raise TypeError("a must be an integer")
+    if not isinstance(b, int):
+        raise TypeError("b must be an integer")
+    if not isinstance(c, int):
+        raise TypeError("c must be an integer")
+    return (x**a + y**b) / c
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    caller = sys._getframe(0).f_globals.get("__name__", "__main__")
+    fn_w_counter.total += 1
+    if caller not in fn_w_counter.callers:
+        fn_w_counter.callers[caller] = 0
+    fn_w_counter.callers[caller] += 1
+    return (fn_w_counter.total, dict(fn_w_counter.callers))
+
+fn_w_counter.total = 0
+fn_w_counter.callers = {}