3. The nth Fibonacci number is defined by the following recursive equations: f(1) = 0; f(2)=1; f(n) = f(n-1) + f(n-2) Therefore the 3rd Fibonacci number is calculated: f(3)=f(2)+f(1)=1+0=1, and so forth for higher numbers. Write a function file to calculate nth Fibonacci number; n is an integer input to the function file and the Fibonacci number is the output argument. Use a for loop to perform the calculation.