How would I be able to complete the solution of this Fibonacci function? The parameters are as follows: It has an index, n, and then it must return the nth value in the sequence. If any negative index values were to exist it should only return -1. Lastly, the output must output the sum of all of the values in the sequence in a single sequence instead of a series. For example, if I were to use the number 8 for my input, I would get 21 as an output and not 8+7+6+5+4+3+2+1.