🧙‍♂️ Python Wizard!

🔍 Quick Lesson

Once you've defined a function in Python, you need to call it in order for it to run. Calling a function executes the code inside it. It's like summoning a spell from your spellbook!

1. Calling a Simple Function

                    def say_hello():
                        print("Hello, wizard!")

                    say_hello()
                

The function say_hello() is called at the bottom, which prints the greeting.

2. Calling Functions with Arguments

If your function requires inputs (parameters), provide them inside the parentheses when you call it:

                    def greet(name):
                        print(f"Hello, {name}!")

                    greet("Merlin")
                

This will output: Hello, Merlin!

3. Using Return Values

You can call a function and capture its return value in a variable:

                    def add(a, b):
                        return a + b

                    result = add(5, 7)
                    print(result)  # Outputs 12
                

4. Calling Functions in Other Functions

Functions can be called inside other functions:

                    def add(a, b):
                        return a + b

                    def multiply_and_add(x, y, z):
                        return x * add(y, z)

                    print(multiply_and_add(2, 3, 4))  # Outputs 14
                

This calls add(3, 4) first (which returns 7), and then multiplies it by 2.

5. Calling Built-in Functions

Python provides many built-in functions you can call without defining them:

• print("Hello") – displays output
• len("magic") – returns the length of a string
• type(10) – returns the data type

6. Function Call Order

You must define a function before you call it. Otherwise, Python will raise an error:

                    say_hello()  # ❌ NameError: name 'say_hello' is not defined

                    def say_hello():
                        print("Hello")
                

Fix this by defining the function before calling it.