 When we think about behaviors, we can think about defining them in multiple ways. One of those ways is called a functional based definition. In other words, we define a behavior in terms of it's an effect on the environment. So flipping on a light switch, the effect of the environment is that the light switch has been flipped. There's the function. Hopefully the light will turn on too, but that's a slightly different issue. So a function based definition is where we provide the function of the behavior or the class of behaviors and its effect on the environment. It's really how it is.