Assigning a Value to a Child Table Field in Frappe or ERPNext

When working with child tables in the Frappe Framework or ERPNext, some functionalities that work out of the box with other DocTypes that aren't child tables may prove to be a pain. In this tutorial, I will quickly brush through the following: 1. How to listen to the add-row event in a child table 2. How to assign a value to a field in a child table on adding a new row 3. How to assign a value to a field in a child table on changing another field in the same child table