# Viewmodel VM has only 2 variables whose updates trigger function updates.

Health Variable

MaxHealth Variable

Functions must always have only one return value, and must also have the attributes: pure and const. Two examples are given below.

GetPercent() Properties

IsAlive() Properties

The following is the content of the functions, for a better understanding of this example.

GetPercent()

GetInvertedPercent()

IsVisible()

IsAlive()

IsDead()

IsFull()