"Session 4" covers two major topics in Dart:

1. Null Safety ◦ What is Null? → Represents the absence of a value. ◦ Operators for Null Safety: ▪ ? → Allows a variable to hold null. ▪ ! → Asserts that a value is non-null. ▪ ?? → Provides a default value if a variable is null.

2. Functions ◦ Defining and calling functions ◦ Types of functions: ▪ Basic functions ▪ Lambda functions ◦ Optional & Named Parameters ◦ Example: Function to combine first and last names with named parameters.

3. Bonus Questions ◦ Function to perform basic arithmetic using named parameters. ◦ Reverse a number using a while loop. ◦ Sum all numbers in a list using forEach. The next session will introduce Object-Oriented Programming (OOP).