diff --git a/python-function/README.md b/python-function/README.md
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+++ b/python-function/README.md
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+# Defining Your Own Python Function
+
+This folder provides the code examples for the Real Python tutorial [Defining Your Own Python Function](https://realpython.com/defining-your-own-python-function/).
diff --git a/python-function/average.py b/python-function/average.py
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+++ b/python-function/average.py
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+def cumulative_average(numbers):
+    total = 0
+    for items, number in enumerate(numbers, 1):
+        total += number
+        yield total / items
+
+
+values = [5, 3, 8, 2, 5]  # Simulates a large data set
+
+for cum_average in cumulative_average(values):
+    print(f"Cumulative average: {cum_average:.2f}")
+
+
+def average(*args):
+    return sum(args) / len(args)
+
+
+print(average(1, 2, 3, 4, 5, 6))
+print(average(1, 2, 3, 4, 5, 6, 7))
+print(average(1, 2, 3, 4, 5, 6, 7, 8))
diff --git a/python-function/calculate.py b/python-function/calculate.py
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+++ b/python-function/calculate.py
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+def calculate(x, y, *, operator):
+    if operator == "+":
+        return x + y
+    elif operator == "-":
+        return x - y
+    elif operator == "*":
+        return x * y
+    elif operator == "/":
+        return x / y
+    else:
+        raise ValueError("invalid operator")
+
+
+calculate(3, 4, operator="+")
+calculate(3, 4, operator="-")
+calculate(3, 4, operator="*")
+calculate(3, 4, operator="/")
diff --git a/python-function/calculations.py b/python-function/calculations.py
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+++ b/python-function/calculations.py
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+def add(a: int | float, b: int | float) -> int | float:
+    return a + b
diff --git a/python-function/closure.py b/python-function/closure.py
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+++ b/python-function/closure.py
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+def function():
+    value = 42
+
+    def closure():
+        print(f"The value is: {value}!")
+
+    return closure
+
+
+reveal_number = function()
+reveal_number()
diff --git a/python-function/cost.py b/python-function/cost.py
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+++ b/python-function/cost.py
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+def calculate_cost(item, quantity, price):
+    print(f"{quantity} {item} cost ${quantity * price:.2f}")
+
+
+print(calculate_cost("bananas", 6, 0.74))
diff --git a/python-function/double.py b/python-function/double.py
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+++ b/python-function/double.py
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+def double(numbers):
+    for i, _ in enumerate(numbers):
+        numbers[i] *= 2
+
+
+numbers = [1, 2, 3, 4, 5]
+print(double(numbers))
diff --git a/python-function/format_name.py b/python-function/format_name.py
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+++ b/python-function/format_name.py
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+def format_name(first_name, last_name, /, title=None):
+    full_name = f"{first_name} {last_name}"
+    if title is not None:
+        full_name = f"{title} {full_name}"
+    return full_name
+
+
+print(format_name("Jane", "Doe"))
+print(format_name("John", "Doe", title="Dr."))
+print(format_name("Linda", "Brown", "PhD."))
diff --git a/python-function/greeting.py b/python-function/greeting.py
new file mode 100644
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+++ b/python-function/greeting.py
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+# def greet(name):
+#     print(f"Hello, {name}!")
+
+
+def greet(name, verbose=False):
+    if verbose:
+        print(f"Hello, {name}! Welcome to Real Python!")
+    else:
+        print(f"Hello, {name}!")
+
+
+greet("Pythonista", verbose=True)
+greet("Pythonista")
diff --git a/python-function/hypotenuse.py b/python-function/hypotenuse.py
new file mode 100644
index 0000000000..f9d01f738f
--- /dev/null
+++ b/python-function/hypotenuse.py
@@ -0,0 +1,2 @@
+def hypotenuse(a, b, /):
+    return (a**2 + b**2) ** 0.5
diff --git a/python-function/mutable_argument.py b/python-function/mutable_argument.py
new file mode 100644
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+++ b/python-function/mutable_argument.py
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+def add_product(item, inventory=[]):
+    inventory.append(item)
+    return inventory
+
+
+print(add_product("apple"))
+print(add_product("banana"))
diff --git a/python-function/network.py b/python-function/network.py
new file mode 100644
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+++ b/python-function/network.py
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+import asyncio
+
+
+async def fetch_data():
+    print("Fetching data from the server...")
+    await asyncio.sleep(1)  # Simulate network delay
+    print("Data received!")
+    return {"user": "john", "status": "active"}
+
+
+async def main():
+    data = await fetch_data()
+    print(f"Received data: {data}")
+
+
+asyncio.run(main())
diff --git a/python-function/power.py b/python-function/power.py
new file mode 100644
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+++ b/python-function/power.py
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+def generate_power(exponent):
+    def power(base):
+        return base**exponent
+
+    return power
+
+
+square = generate_power(2)
+print(square(4))
+print(square(6))
+
+cube = generate_power(3)
+print(cube(3))
+print(cube(5))
diff --git a/python-function/reader.py b/python-function/reader.py
new file mode 100644
index 0000000000..9b0a8a1227
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+++ b/python-function/reader.py
@@ -0,0 +1,15 @@
+from pathlib import Path
+
+
+def read_file_contents(file_path):
+    path = Path(file_path)
+
+    if not path.exists():
+        print(f"Error: The file '{file_path}' does not exist.")
+        return
+
+    if not path.is_file():
+        print(f"Error: '{file_path}' is not a file.")
+        return
+
+    return path.read_text(encoding="utf-8")
diff --git a/python-function/report.py b/python-function/report.py
new file mode 100644
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+++ b/python-function/report.py
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+def report(**kwargs):
+    print("Report:")
+    for key, value in kwargs.items():
+        print(f" - {key.capitalize()}: {value}")
+
+
+report(
+    name="Keyboard",
+    price=19.99,
+    quantity=5,
+    category="PC Components",
+)
diff --git a/python-function/sum.py b/python-function/sum.py
new file mode 100644
index 0000000000..ecf824257f
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+++ b/python-function/sum.py
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+def sum_numbers(*numbers, precision=2):
+    return round(sum(numbers), precision)
+
+
+print(sum_numbers(1.3467, 2.5243, precision=3))
+print(sum_numbers(1.3467, 2.5243, 3))
diff --git a/python-function/unpacking.py b/python-function/unpacking.py
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+++ b/python-function/unpacking.py
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+# def function(x, y, z):
+#     print(f"{x = }")
+#     print(f"{y = }")
+#     print(f"{z = }")
+
+
+# numbers = [1, 2, 3]
+
+# function(*numbers)
+
+
+# def function(one, two, three):
+#     print(f"{one = }")
+#     print(f"{two = }")
+#     print(f"{three = }")
+
+
+# numbers = {"one": 1, "two": 2, "three": 3}
+# function(**numbers)
+
+
+def function(**kwargs):
+    for key, value in kwargs.items():
+        print(key, "->", value)
+
+
+numbers = {"one": 1, "two": 2, "three": 3}
+letters = {"a": "A", "b": "B", "c": "C"}
+
+function(**numbers, **letters)
diff --git a/python-function/users.py b/python-function/users.py
new file mode 100644
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--- /dev/null
+++ b/python-function/users.py
@@ -0,0 +1,15 @@
+def find_user(username, user_list):
+    for user in user_list:
+        if user["username"] == username:
+            return user
+    return None
+
+
+users = [
+    {"username": "alice", "email": "alice@example.com"},
+    {"username": "bob", "email": "bob@example.com"},
+]
+
+find_user("alice", users)
+
+print(find_user("linda", users))