Typedef for the Response function type. A response function takes a value (typically normalized into the range 0-1) and returns a transformation of that value, typically also clamped to the range 0-1. These functions are used to calculate a utility score for a Consideration by processing the value of an Input, which usually originates in the game world. This is response curves in the sense of Bob Alexander in AI Game Programming Wisdom - The Beauty of Response Curves, not a "Best Response" curve in game theory.