Course Content

Python Functions Tutorial

1. What is Function in Python?

What Is Function?Challenge: Building functions Arguments Return Value Function Body Built-in Functions

2. Positional and Optional Arguments

Positional Arguments Challenge: Positional Arguments Optional Arguments Challenge: Optional Arguments

3. Arbitrary Arguments

Arbitrary Arguments Arbitrary Keyword Arguments Combination of Positional and Optional Arguments

4. Function Return Value Specification

Single Return Value Multiple Return Values None Return Value Generator Functions Challenge: Traffic lights

5. Recursion and Lambda Functions

Recursion Challenge: Pyramid Lambda Functions Immediately Invoked Lambda Expression Writing Effective and Maintainable Functions

Built-in Functions

Built-in functions in Python are pre-defined functions readily available for use in any Python program without requiring additional specifications or definitions. One of the built-in functions is the print() function - we have already used it. We didn't need to define this function, write its body and specify the return value - we just called it and provided inputs. There are many built-in functions in Python. Now we will consider the most commonly used:

print(): Outputs a specified message or variable to the console:


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print("My message")

len(): Returns the length (number of elements) of an object, such as a string, list, or tuple:


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word = "Codefinity"
print("Word length:", len(word))

sum(): Calculates the sum of a sequence of numbers:


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numbers = [5, 2, 3]
print("Sum of numbers:", sum(numbers))

max() and min(): Returns the maximum/ minimum value from a sequence:


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numbers = [5, 2, 3]
print("The largest among the numbers:", max(numbers))
print("The smallest of the numbers:", min(numbers))

You may have already been familiar with these functions before, or maybe not. The key in this section is to see the difference between built-in functions and your own.

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Section 1. Chapter 6