> ## Documentation Index
> Fetch the complete documentation index at: https://python-training.ipoint-labs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Lab 26: Days in a month

> Hands-on lab · 20 min · Module 10

Write `days_in_month(year, month)`, which calls `is_leap()`, returns early with `None` for a month that doesn't exist, and feeds a sentence about the month.

[Open Lab 26 in the IP Lab Portal](https://labs.intellectualpoint.com/labs/pcep-lab-26-days-in-month)

## What you will practice

* Call one function from another
* Return early for invalid input
* Return `None` when there is no answer

## Before you start

Time
20 minutes
*Hands-on in Python 3*

Where
IP Lab Portal
*labs.intellectualpoint.com*

Module
Module 10: Defining functions
*PCEP-30-03*

* In the IP Lab Portal, open **Lab 26 - Days in a month**.
* In class, this lab comes right after the **Lesson 3 recap** slide in [Module 10 core material](https://python-training.ipoint-labs.com/pcep/module-10/material.md).


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