``` fib 0 = 0 fib 1 = 1 fib n = fib(n - 1) + fib(n - 2) ``` <img width="468" alt="image" src="https://github.com/erg-lang/web-ide/assets/15035783/f2b2a205-b662-40dd-9f00-b5c5dfa1bc02">
