fib1 :: Integer -> Integer
fib1 n
  | n == 0 || n == 1 = n
  | otherwise = fib1 (n - 1) + fib1 (n - 2)
fib1 :: Integer -> Integer
fib1 n
  | n == 0 || n == 1 = n
  | otherwise = fib1 (n - 1) + fib1 (n - 2)
fib1 n
  | n == 0 || n == 1 = n
  | otherwise = fib1 (n - 1) + fib1 (n - 2)