Challenge B: Closure sums

In this challenge, you’re going to write a function that you can reuse to create different mathematical sums.

Declare the function like so:

func mathSum(length: Int, series: (Int) -> Int) -> Int

The first parameter, length, defines the number of values to sum. The second parameter, series, is a closure that can be used to generate a series of values. series should have a parameter that is the position of the value in the series and return the value at that position.

mathSum should calculate length number of values, starting at position 1, and return their sum.

Use the function to find the sum of the first 10 square numbers, which equals 385. Then use the function to find the sum of the first 10 Fibonacci numbers, which equals 143. For the Fibonacci numbers, you can use the function you wrote in the functions chapter — or grab it from the solutions if you’re unsure your solution is correct.