Write a program that calculates the weekly income based on the normal hours and after hours of an employee. The rate for the normal hours is $30 per hours and the rate for the after hours is $40 per hours.
Note: You must write three functions: one to calculate the income from normal working hours, one to calculate the income from after hours and the last one to calculate the total income.
Also, please do not forget to include as much as possible comments for your code.