Keyword arguments

def greet(name, age):
    print("Hello, " + name + "! You are " + str(age) + " years old.")

greet(name="John", age=15)  # Output: Hello, John! You are 15 years old.

def greet(name, age=18):
    print("Hello, " + name + "! You are " + str(age) + " years old.")

greet(name="John")  # Output: Hello, John! You are 18 years old.
greet(name="Alice", age=20)  # Output: Hello, Alice! You are 20 years old.