diff --git a/Week04/decorators_beyza_arman.py b/Week04/decorators_beyza_arman.py
new file mode 100644
index 00000000..2aa037ee
--- /dev/null
+++ b/Week04/decorators_beyza_arman.py
@@ -0,0 +1,29 @@
+from functools import wraps
+from time import perf_counter
+import tracemalloc
+
+
+def performance(function):
+    """Measure calls, elapsed time and peak traced memory."""
+    @wraps(function)
+    def wrapper(*args, **kwargs):
+        owns_tracing = not tracemalloc.is_tracing()
+        if owns_tracing:
+            tracemalloc.start()
+        before, _ = tracemalloc.get_traced_memory()
+        start = perf_counter()
+        try:
+            return function(*args, **kwargs)
+        finally:
+            performance.counter += 1
+            performance.total_time += perf_counter() - start
+            _, peak = tracemalloc.get_traced_memory()
+            performance.total_mem += max(0, peak - before)
+            if owns_tracing:
+                tracemalloc.stop()
+    return wrapper
+
+
+performance.counter = 0
+performance.total_time = 0.0
+performance.total_mem = 0
diff --git a/Week04/functions_beyza_arman.py b/Week04/functions_beyza_arman.py
new file mode 100644
index 00000000..ae6e83b7
--- /dev/null
+++ b/Week04/functions_beyza_arman.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:
+    """Calculate a sum of powers divided by c.
+
+    :param x: First base.
+    :param y: Second base.
+    :param a: Exponent of x.
+    :param b: Exponent of y.
+    :param c: Divisor.
+    :return: The value of (x**a + y**b) / c.
+    :raises TypeError: If an argument is not an integer.
+    """
+    if not all(isinstance(value, int) for value in (x, y, a, b, c)):
+        raise TypeError("All arguments must be integers")
+    return (x ** a + y ** b) / c
+
+
+def fn_w_counter() -> (int, dict[str, int]):
+    """Count calls and keep a per-module record."""
+    fn_w_counter.counter += 1
+    calls = fn_w_counter.calls
+    calls[__name__] = calls.get(__name__, 0) + 1
+    return fn_w_counter.counter, dict(calls)
+
+
+fn_w_counter.counter = 0
+fn_w_counter.calls = {}