Guarantees

Suppose you have a function in C# with the following signature:

int f(int i) { ... }

Given this signature, can you guarantee to me what the return type of the function is? Seems like a no brainer, right? Not so fast... examine this code for a second:

int f(int i) { return i / 0; }

In this instance, function f will not return an int at all, but it will rather raise an exception. I just wanted to illustrate the point that even in a statically typed language like C#, there is no guarantee that you will get back exactly what the language is advertising to you.