The Fibonacci sequence begins with 0 and then 1 follows. All subsequent values are the sum of the previous two, ex: 0, 1, 1, 2, 3, 5, 8, 13. Complete the fibonacci() function, which has an index n as...

Extracted text: The Fibonacci sequence begins with 0 and then 1 follows. All subsequent values are the sum of the previous two, ex: 0, 1, 1, 2, 3, 5, 8, 13. Complete the fibonacci() function, which has an index n as parameter and returns the nth value in the sequence. Any negative index values should return -1. Ex: If the input is: 7 the output is: fibonacci (7) is 13 Note: Use a for loop and DO NOT use recursion.