fibonacci series   can someone please explain the last return line .

# Function for nth Fibonacci number

def Fibonacci(n):

    if n<= 0:

        print("Incorrect input")

    # First Fibonacci number is 0

    elif n == 1:

        return 0

    # Second Fibonacci number is 1

    elif n == 2:

        return 1

    else:

        return Fibonacci(n-1)+Fibonacci(n-2)

# Driver Program

print(Fibonacci(10))

# This code is contributed by Saket Modi