Create a function that returns the amount of Fibonacci numbers strictly smaller than the given integer. In mathematics, the Fibonacci numbers commonly denoted Fn, form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. Thus:
F0=0 and F1=1
and
Fn=F(n-1)+F(n-2)
for n > 1
The beginning of the sequence is thus:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...
The function should thus return 13 when called with the variable n = 145 since there exist 13 Fibonacci numbers strictly smaller than 145.
amount_fib(0) ➞ 0
amount_fib(1) ➞ 1
amount_fib(3) ➞ 4
amount_fib(22) ➞ 9
amount_fib(145) ➞ 13
N/A