[C++] Implement the following function:

double get_nth_fibonacci_number(size_t n);

which returns the nth number in the Fibonacci sequence. The first two terms of the sequence are both 1. Thereafter successive terms are simply the sums of their two previous terms. Thus

the sequence goes:

1, 1, 2, 3, 5, 8, 13, 21, . . .

double get_nth_fibonacci_number(size_t n) {

// TODO - Your code here

// You may not use the Math library methods

// Instead, use the loop to solve this.

}