Docstrings and documentation in Python - Step-by-Step Execution

Concept Flow - Docstrings and documentation

Define function

↓

Add docstring inside triple quotes

↓

Function body code

↓

Call help() or __doc__ to read docstring

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See documentation output

This flow shows how to write a docstring inside a function and then access it using help() or __doc__.

Execution Sample

Python

def greet(name):
    """Return a greeting message for the given name."""
    return f"Hello, {name}!"

print(greet.__doc__)

Defines a function with a docstring and prints the docstring.

Execution Table

Step	Action	Evaluation	Result
1	Define function greet with docstring	Store function object with docstring	Function greet created with docstring
2	Call greet.__doc__	Access docstring attribute	Return a greeting message for the given name.
3	Print docstring	Output string to console	Return a greeting message for the given name.
4	End	No more code	Execution stops

💡 All code executed, docstring printed, program ends

Variable Tracker

Variable	Start	After 1	After 2	Final
greet	undefined	function object with docstring	same	same
greet.__doc__	undefined	docstring string	same	same

Key Moments - 3 Insights

Why do we use triple quotes for docstrings instead of single or double quotes?

Triple quotes allow the docstring to span multiple lines and are the standard for documentation strings, as shown in step 1 of the execution_table.

How do we access the docstring after defining the function?

We access it using the __doc__ attribute or the help() function, demonstrated in step 2 of the execution_table.

Does the docstring affect the function's behavior or output?

No, the docstring is only for documentation and does not change how the function runs, as seen in step 3 where only the docstring is printed.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of greet.__doc__ at step 2?

A Return a greeting message for the given name.

B None

C "Hello, {name}!"

D Function object

💡 Hint

Check the 'Evaluation' column in row 2 of the execution_table.

At which step does the program print the docstring to the console?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Result' columns in the execution_table.

If we remove the docstring, what would greet.__doc__ return?

A An empty string ""

B None

C An error

D The function code

💡 Hint

Recall that __doc__ is None if no docstring is provided.

Concept Snapshot

Docstrings are triple-quoted strings inside functions.
They describe what the function does.
Access them with function.__doc__ or help(function).
They do not affect function behavior.
Use them to make code easier to understand.

Full Transcript

This visual execution shows how to write and use docstrings in Python. First, we define a function with a triple-quoted string right after the function header. This string is the docstring and explains what the function does. The function body follows. When we access the function's __doc__ attribute, we get the docstring text. Printing this shows the documentation message. Docstrings help programmers understand code without changing how the code runs.